Method for controlling communication connection in wireless power transmission system, and apparatus therefor

ABSTRACT

The present invention relates to wireless power transmission. A method for controlling a communication connection for a wireless charging device supporting in-band communication and out-band communication, according to an embodiment of the present invention, may comprise: a step of receiving a first packet from a device through in-band communication; a step of generating a power transmission contract on the basis of the first packet; a step of performing an out-band communication connection on the basis of the power transmission contract; a step of controlling power by using out-band communication when the out-band communication connection is successful.

TECHNICAL FIELD

The present disclosure relates to wireless power transfer, and moreparticularly, to a method of controlling communication connection in awireless power transfer system capable of in-band communication andout-band communication and apparatus therefor.

BACKGROUND ART

The wireless power transfer technology is a technology for wirelesslytransferring power between a power source and an electronic device. Forexample, the wireless power transfer technology enables charging of thebattery of a wireless terminal such as a smartphone or tablet by simplyplacing the wireless terminal on a wireless charging pad, therebyproviding better mobility, convenience, and safety than wired chargingusing cable charging connectors. The wireless power transfer technologyis attracting attention as a replacement for the wired power transfersystem in various fields such as electric vehicles, wearable devicessuch as Bluetooth earphones and 3D glasses, home appliances, furniture,underground facilities, buildings, medical devices, robots, and leisure,in addition to wireless charging of wireless terminals.

The wireless power transfer method is also referred to as a contactlesspower transfer method, a power transfer method with no point of contact,or a wireless charging method. The wireless power transfer systemincludes a wireless power transmitter configured to supply electricalenergy based on the wireless power transfer method and a wireless powerreceiver configured to receive the electrical energy wirelessly suppliedfrom the wireless power transmitter and provide the power to a powerreceiving device such as a battery cell.

The wireless power transfer technology includes various power transfermethods: a power transfer method based on magnetic coupling, a powertransfer method based on radio frequency (RF), a power transfer methodbased on microwaves, a power transfer method based on ultrasonic waves,and so on. The magnetic coupling-based method is further classified intoa magnetic induction method and a magnetic resonance method. Themagnetic induction method is a method of transferring energy based on acurrent induced in the coil of a receiver due to a magnetic fieldgenerated by the coil battery cell of the transmitter according toelectromagnetic coupling between the coil of the transmitter and thecoil of the receiver. The magnetic resonance method is similar to themagnetic induction method in that the magnetic field is used. However,the magnetic resonance method is different from the magnetic inductionmethod in that resonance occurs when a specific resonant frequency isapplied to the coil of the transmitter and the coil of the receiver.

DISCLOSURE Technical Problem

One object of the present disclosure is to provide a wireless powertransmitter, a wireless power transmission method, a wireless powerreceiver, a wireless power reception method, and a wireless chargingsystem.

Another object of the present disclosure is to provide a method ofcontrolling communication connection in a wireless power transfer systemsupporting in-band communication and out-band communication andapparatus therefor.

Another object of the present disclosure is to provide a method ofcontrolling communication connection in a wireless power transfer systemcapable of performing handover between in-band and out-bandindependently of a wireless power state machine and apparatus therefor.

Another object of present disclosure is to provide a method ofcontrolling communication connection in a wireless power transfer systemcapable of performing out-band reconnection at all phases based on apower transfer contract without initialization to a selection phase inhandover failure from in-band to out-band by maintaining out-bandsupport and connection state information in the power transfer contractand apparatus therefor.

Another object of the present disclosure is to provide a method ofcontrolling communication connection in a wireless power transfer systemcapable of enhancing security due to a random MAC address transmitted bya wireless power receiver in in-band mode at all wireless chargingphases and apparatus therefor.

Another object of the present disclosure is to provide a method ofcontrolling communication connection in a wireless power transfer systemcapable of improving communication reliability by performing handoverbetween in-band and out-band adaptively depending on changes in powerdemand, communication volume, and communication quality during wirelesscharging and apparatus therefor.

Another object of the present disclosure is a method of controllingcommunication connection in a wireless power transfer system capable ofpreventing wireless charging interruption and improve charging speeds byenabling fast and repeatable reconnection attempts in out-band mode andapparatus therefor.

A further object of the present disclosure is to provide a wirelesspower transmitter and wireless power receiver having two or moremutually complementary communication modules.

Technical Solution

Specific features of the present disclosure are described below.

In an aspect of the present disclosure, a method of controlling acommunication connection by a wireless charger supporting in-bandcommunication and out-band communication is provided. The method mayinclude: receiving a first packet from a device through the in-bandcommunication; creating a power transfer contract based on the firstpacket; establishing an out-band communication connection based on thepower transfer contract; and performing power control through theout-band communication based on success of the out-band communicationconnection.

In an embodiment, the method may include: performing handover toout-band by entering a handover phase according to the power transfercontract; and maintaining the power transfer contract and performing anout-band reconnection procedure based on failure of the handover.

In an embodiment, the out-band reconnection procedure may include:receiving a second packet including a random address from the devicethrough the in-band communication; and registering the device related tothe random address in a whitelist. The out-band reconnection proceduremay be performed with a device included in the whitelist.

In an embodiment, the out-band reconnection procedure may beperiodically repeated.

In an embodiment, the first packet may include a handover flag, and thefirst packet may be received in a configuration phase of a statemachine.

In an embodiment, the power transfer contract may include information onwhether the device supports the out-band communication and informationan out-band communication connection state. Whether the out-bandcommunication is supported may be determined based on the handover flag,and the power transfer contract may be renewed based on the success ofthe out-band communication connection.

In an embodiment, the power transfer contract may be renewed in arenegotiation phase of the state machine.

In an embodiment, the out-band communication may be Bluetooth Low Energy(BLE) communication.

In an embodiment, the method may include: detecting a timeout of theout-band communication; determining whether the device supports theout-band communication based on the power transfer contract; determiningan out-band communication connection state with the device based on thepower transfer contract; and performing the out-band reconnectionprocedure based on the out-band communication being supported and theout-band communication being not connected. When the out-bandcommunication is not supported, charging may be stopped and the statemachine may be initialized.

In an embodiment, the method may include: transmitting a write requestpacket requesting to change communication based on the out-bandcommunication being supported and the out-band communication beingconnected; and switching to the out-band communication based onreception of a response packet for the write request packet. Thecharging may be stopped and the state machine may be initialized whenthe response packet is not received.

Advantageous Effects

As is apparent from the above description, the present disclosure haseffects as follows.

The present disclosure may provide a method of adaptively controllingcommunication connection in a wireless power transfer system supportingin-band communication and out-band communication and apparatus therefor.

The present disclosure may provide a method of controlling communicationconnection in a wireless power transfer system capable of preventingmutual influence between a wireless power state machine and acommunication module in advance by performing handover between in-bandand out-band independently of the wireless power state machine andapparatus therefor.

The present disclosure may provide a method of controlling communicationconnection in a wireless power transfer system capable of performingout-band reconnection at all phases based on a power transfer contractwithout initialization to a selection phase in handover failure fromin-band to out-band by maintaining out-band support and connection phaseinformation in the power transfer contract and apparatus therefor.

The present disclosure may provide a method of controlling communicationconnection in a wireless power transfer system capable of enhancingsecurity due to a random MAC address transmitted by a wireless powerreceiver in in-band mode at all wireless charging phases and apparatustherefor.

The present disclosure may provide a method of controlling communicationconnection in a wireless power transfer system capable of improvingcommunication reliability by performing handover between in-band andout-band adaptively depending on changes in the communicationenvironment such as changes in power demand, communication volume, andcommunication quality during wireless charging and apparatus therefor.

The present disclosure may provide a method of controlling communicationconnection in a wireless power transfer system capable of preventingwireless charging interruption and improve charging speeds by enablingfast and repeatable reconnection attempts in out-band mode and apparatustherefor

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a wireless power system 10 according to anembodiment of the present disclosure.

FIG. 2 is a block diagram of the wireless power system 10 according toanother embodiment of the present disclosure.

FIG. 3A illustrates examples of various electronic devices to which awireless power transfer system is introduced.

FIG. 3B illustrates an exemplary Wireless Power Consortium (WPC)near-field communication (NFC) data exchange profile format (NDEF) in awireless power transfer system.

FIG. 4A is a block diagram of a wireless power transfer system accordingto another embodiment of the present disclosure.

FIG. 4B is a diagram illustrating an exemplary Bluetooth communicationarchitecture to which the present disclosure is applicable.

FIG. 4C is a block diagram illustrating a wireless power transfer systemusing Bluetooth Low Energy (BLE) communication according to anembodiment of the present disclosure.

FIG. 4D is a block diagram illustrating a wireless power transfer systemusing BLE communication according to another embodiment of the presentdisclosure.

FIG. 5 is a state transition diagram for explaining a wireless powertransfer procedure.

FIG. 6 illustrates a power control method according to an embodiment ofthe present disclosure.

FIG. 7 is a block diagram of a wireless power transmitter according toanother embodiment of the present disclosure.

FIG. 8 illustrates a wireless power receiver according to anotherembodiment of the present disclosure.

FIG. 9 illustrates a communication frame structure according to anembodiment of the present disclosure.

FIG. 10 illustrates a structure of a synchronization pattern accordingto an embodiment of the present disclosure.

FIG. 11 illustrates operating states of a wireless power transmitter andreceiver in a shared mode according to an embodiment of the presentdisclosure.

FIG. 12 is a block diagram illustrating a wireless charging certificateformat according to an embodiment of the present disclosure.

FIG. 13 illustrates a structure of a capability packet of a wirelesspower transmitter according to an embodiment of the present disclosure.

FIG. 14 illustrates a structure of a configuration packet of a wirelesspower receiver according to an embodiment of the present disclosure.

FIG. 15 illustrates an application-level data stream between a wirelesspower transmitter and receiver according to an embodiment of the presentdisclosure.

FIG. 16 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to an embodiment of the presentdisclosure.

FIG. 17 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to another embodiment of the presentdisclosure.

FIG. 18 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to a further embodiment of thepresent disclosure.

FIG. 19 is a block diagram illustrating state machines for power class 0(PC0) and power class 1 (PC1) according to an embodiment of the presentdisclosure.

FIG. 20 is a diagram for explaining a method of adding information onwhether out-band (i.e., BLE) is supported and information on aconnection state to a power contract according to an embodiment of thepresent disclosure.

FIG. 21 is a flowchart illustrating a procedure for renewing a powertransfer contract according to an embodiment of the present disclosure.

FIG. 22 is a flowchart illustrating a procedure for renewing a powertransfer contract according to another embodiment of the presentdisclosure.

FIG. 23 illustrates a timeout procedure in case of packet loss.

FIG. 24 is a functional block diagram of a wireless power transmitter orreceiver according to an embodiment of the present disclosure.

FIG. 25 is a flowchart illustrating a method by which a wireless powertransmitter and/or wireless power receiver controls a communicationconnection according to an embodiment of the present disclosure.

FIG. 26 is a flowchart illustrating a method by which a wireless powertransmitter and/or wireless power receiver controls a communicationconnection according to another embodiment of the present disclosure.

BEST MODE

In an embodiment of the present disclosure, a method of controlling acommunication connection by a wireless charger supporting in-bandcommunication and out-band communication is provided. The method mayinclude: receiving a first packet from a device through the in-bandcommunication; creating a power transfer contract based on the firstpacket; establishing an out-band communication connection based on thepower transfer contract; and performing power control through theout-band communication based on success of the out-band communicationconnection.

MODE FOR THE DISCLOSURE

The term “wireless power” used hereinafter refers to any form of energyrelated to electric, magnetic, and electromagnetic fields transferredfrom a wireless power transmitter to a wireless power receiver withoutthe use of physical electromagnetic conductors. Wireless power may becalled a wireless power signal and may refer to an oscillating magneticflux enclosed by primary and secondary coils. For example, this documentdescribes power conversion in a system for charging devices including amobile phone, cordless phone, iPod, MP3 player, and headset wirelessly.In general, the basic principles of wireless power transfer includepower transfer based on magnetic coupling, power transfer based on radiofrequency (RF), power transfer based on microwaves, and power transferbased on ultrasonic waves.

FIG. 1 is a block diagram of a wireless power system 10 according to anembodiment of the present disclosure.

Referring to FIG. 1, the wireless power system 10 includes a wirelesspower transmitter 100 and a wireless power receiver 200.

The wireless power transmitter 100 receives power from an external powersource S and generates a magnetic field. The wireless power receiver 200receives power wirelessly by generating currents based on the generatedmagnetic field.

The wireless power transmitter 100 and the wireless power receiver 200in the wireless power system 10 may transmit and receive various piecesof information required for wireless power transfer. Here, communicationbetween the wireless power transmitter 100 and the wireless powerreceiver 200 may be performed according to either in-band communicationusing a magnetic field for wireless power transfer or out-bandcommunication using a separate communication carrier. Out-bandcommunication may also be called out-of-band communication. In thefollowing, the terms are unified as out-band communication. For example,out-band communication includes near-field communication (NFC),Bluetooth, and Bluetooth Low Energy (BLE).

Here, the wireless power transmitter 100 may be a fixed or mobile typeof wireless power transmitter. For example, the fixed type oftransmitter includes a transmitter embedded in an indoor ceiling or wallor furniture such as a table; a transmitter implanted in an outdoorparking lot, bus stop or subway station; or a transmitter installed in atransportation such as a vehicle or train. The mobile type of wirelesspower transmitter may be implemented as a mobile device with a portableweight or size or as part of another device such as a laptop computercover.

The wireless power receiver 200 should be construed as a comprehensiveconcept including various types of electronic devices equipped with abattery and various home appliances driven by receiving power wirelesslyrather than a power cable. Typical examples of the wireless powerreceiver 200 include a portable terminal, cellular phone, smartphone,personal digital assistant (PDA), portable media player (PMP), Wibroterminal, tablet, phablet, laptop computer, digital camera, navigationterminal, television, and electric vehicle (EV).

The wireless power system 10 may include one or a plurality of wirelesspower receivers 200. Although FIG. 1 illustrates a case where thewireless power transmitter 100 and the wireless power receiver 200transmit and receive power one-to-one, one wireless power transmitter100 transmits power to a plurality of wireless power receivers 200-1,200-2, . . . , 200-M. In particular, when wireless power transfer isconducted based on magnetic resonance, one wireless power transmitter100 may simultaneously transmit power to multiple wireless powerreceivers 200-1, 200-2, . . . , 200-M by applying simultaneoustransmission or time-division transmission.

Although FIG. 1 illustrates a case where the wireless power transmitter100 transmits power directly to the wireless power receiver 200, awireless power transceiver such as a relay or repeater for increasingthe range of wireless power transmission may be provided between thewireless power transmitter 100 and the wireless power receiver 200. Inthis case, the wireless power transmitter 100 may transmit power thewireless power transceiver, and the wireless power transceiver maytransmit the power to the wireless power receiver 200.

In this document, the wireless power receiver 200 refers to a wirelesspower receiver, a power receiver, and a receiver. Also, the wirelesspower transmitter 100 refers to a wireless power transmitter, a powertransmitter, and a transmitter.

FIG. 3A illustrates examples of various electronic devices where awireless power transfer system is introduced.

In FIG. 3A, electronic devices are categorized according to the amountof transferred power in a wireless power transmission system. Referringto FIG. 3A, low power wireless charging (smaller than about 5 or 20 W)may be applied to wearable devices such as a smart watch, head mounteddisplay (HMD), smart ring, and smart glasses and mobile electronicdevices (or portable electronic devices) such as an earphone, remotecontroller, smartphone, PDA, and tablet PC.

Medium power wireless charging (smaller than about 50 or 200 W) may beapplied to small and medium-sized home appliances such as a laptopcomputer, robot cleaner, TV, sound device, vacuum cleaner, and monitor.High power wireless charging (small than about 2 or 22 kW) may beapplied to kitchen appliances such as a blender, microwave oven, andelectric rice cooker; and personal mobility devices (or electricdevice/mobility means) such as a wheelchair, electric kickboard,electric bicycle, and electric vehicle.

The electronic devices/mobility means described above (or shown inFIG. 1) may each include a wireless power receiver, which will bedescribed later. Therefore, the above-described electronicdevices/mobility means may be charged by receiving power wirelessly froma wireless power transmitter.

The present disclosure will be described based on a mobile device towhich wireless power charging is applied, but this is merely exemplary.That is, the wireless charging method according to the presentdisclosure may be applied to various electronic devices.

Wireless power transfer standards include those studied by WirelessPower Consortium (WPC), Air Fuel Alliance (AFA), and Power MattersAlliance (PMA).

WPC standards define baseline power profile (BPP) and extended powerprofile (EPP). BPP is related to wireless power transmitters andreceivers that support power transmission of 5 W, and EPP is related towireless power transmitters and receivers that support powertransmission in the range of 5 and 30 W.

Each standard covers various wireless power transmitters and receiversusing different power levels and also classifies the wireless powertransmitters and receivers into different power classes or categories.

For example, the WPC classifies wireless power transmitters andreceivers in terms of power classes (PC): PC-1, PC0, PC1, and PC2 andprovides standard specifications for each PC. The PC-1 standard isrelated to wireless power transmitters and receivers that provideguaranteed power less than 5 W. PC-1 applications include wearabledevices such as smart watches.

The PC0 standard is related to wireless power transmitters and receiversthat provide guaranteed power of 5 W. The PC0 standard includes the EPPin which guaranteed power reaches up to 30 W. Although in-band (IB)communication is a mandatory communication protocol for PC0, out-band(OB) communication, which is used as an optional backup channel, mayalso be used for PC0. Whether a wireless power receiver supports OB maybe identified by configuring an OB flag in a configuration packet. Ifthe wireless power transmitter supports OB, the wireless powertransmitter may enter an OB handover phase by transmitting a bit patternfor OB handover as a response to the configuration packet. The responseto the configuration packet may be an NAK, an ND, or a newly defined8-bit pattern. PC0 applications include smartphones.

The PC1 standard is related to wireless power transmitters and receiversproviding guaranteed power ranging from 30 W to 150 W. OB is a mandatorycommunication channel for PC1, and IB is used for initialization andlink establishment to OB. The wireless power transmitter may enter theOB handover phase by transmitting the bit pattern for OB handover as aresponse to the configuration packet. PC1 applications include laptopcomputers or power tools.

The PC2 standard is related to wireless power transmitters and receiversproviding guaranteed power ranging from 200 W to 2 kW. PC2 applicationsinclude kitchen appliances.

As described above, PCs may be divided based on power levels, andcompatibility within the same PC may be optional or mandatory. Here, thecompatibility within the same PC means that power transmission andreception is allowed within the same PC. For example, if a wirelesspower transmitter of PC x is capable of charging a wireless powerreceiver with the same PC (i.e., PC x), it may be regarded thatcompatibility is maintained within the same PC. Similarly to the above,compatibility between different PCs may also be supported. Here, thecompatibility between different PCs means that power transmission andreception is allowed between different PCs. For example, if a wirelesspower transmitter of PC x is capable of charging a wireless powerreceiver with PC y, it may be regarded that compatibility is maintainedbetween different PCs.

The support of compatibility between PCs is an important issue in termsof user experience and infrastructure development. However, maintainingthe compatibility between PCs may cause various technical problems asfollows.

For example, when compatibility within the same PC is supported, awireless power receiver such a laptop, which is stably charged only whenpower is transmitted continuously, may have a problem in receiving powerreliably from a wireless power transmitter such as a power tool schemethat transmits power discontinuously. When compatibility betweendifferent PCs is supported, for example, if a wireless power transmitterwith minimum guaranteed power of 200 W transmits power to a wirelesspower receiver with maximum guaranteed power is 5 W, the wireless powerreceiver may be damaged due to overvoltage. As a result, it is difficultto take the PC as an indicator/reference for representing/indicatingcompatibility.

Wireless power transmitters and receivers may provide very convenientuser experience and interface (UX/UI). In other words, a smart wirelesscharging service may be provided. The smart wireless charging servicemay be implemented based on the UX/UI of a smartphone including thewireless power transmitter. For such an application, an interfacebetween the processor of the smartphone and the wireless power receiverallows “drop and play” two-way communication between the wireless powertransmitter and receiver.

For example, a user may experience the smart wireless charging serviceat a hotel. If the user enters a hotel room and places the smartphone ona wireless charger in the room, the wireless charger transmits wirelesspower to the smartphone, and the smartphone receives the wireless power.In this process, the wireless charger transmits, to the smartphone,information about the smart wireless charging service. If the smartphonedetects that it is placed on the wireless charger, detects the wirelesspower reception, or receives the information about the smart wirelesscharging service from the wireless charger, the smartphone enters astate for asking the user to opt-in into an additional feature. To thisend, the smartphone may display a message on the screen with or withoutan alarm sound. For example, the message may include the followingsentences: “Welcome to ### hotel. Select “Yes” to activate smartcharging functions: Yes|No Thanks.” The smartphone receives a user inputselecting Yes or No Thanks and performs the next procedure selected bythe user. If Yes is selected, the smartphone transmits the correspondinginformation to the wireless charger. The smartphone and the wirelesscharger perform the smart charging function together.

The smart wireless charging service may also include receivingauto-filled WiFi credentials. For example, the wireless chargertransmits WiFi credentials to the smartphone, and the smartphoneautomatically inputs the WiFi credentials received from the wirelesscharger by executing an appropriate app.

The smart wireless charging service may also include executing a hotelapplication that provides hotel promotions or obtaining remotecheck-in/check-out and contact information.

In another example, a user may experience the smart wireless chargingservice inside a vehicle. If the user gets into the vehicle and placesthe smartphone on a wireless charger, the wireless charger transmitswireless power to the smartphone, and the smartphone receives thewireless power. In this process, the wireless charger transmitsinformation about the smart wireless charging service to the smartphone.If the smartphone detects that it is placed on the wireless charger,detects the wireless power reception, or receives the information aboutthe smart wireless charging service from the wireless charger, thesmartphone enters a state for asking the user about the identity.

In this state, the smartphone is automatically connected to the vehiclevia WiFi and/or Bluetooth. The smartphone may display a message on thescreen with or without an alarm sound. For example, the message mayinclude the following sentences: “Welcome to your car. Select “Yes” tosynch device with in-car controls: Yes|No Thanks.” The smartphonereceives a user input selecting Yes or No Thanks and performs the nextprocedure selected by the user. If Yes is selected, the smartphonetransmits the corresponding information to the wireless charger. Thesmartphone and wireless charger may perform an in-vehicle smart controlfunction together by executing in-vehicle application/display software.The user may enjoy desired music and check a regular map location. Thein-vehicle application/display software may include a function thatprovides synchronization access for passers-by.

In another example, a user may experience smart wireless charging athome. If the user enters a room and places the smartphone on a wirelesscharger in the room, the wireless charger transmits wireless power tothe smartphone, and the smartphone receives the wireless power. In thisprocess, the wireless charger transmits, to the smartphone, informationabout the smart wireless charging service. If the smartphone detectsthat it is placed on the wireless charger, detects the wireless powerreception, or receives the information about the smart wireless chargingservice from the wireless charger, the smartphone enters a state forasking the user to opt-in into an additional feature. To this end, thesmartphone may display a message on the screen with or without an alarmsound. For example, the message may include the following sentences: “Hixxx, would you like to activate night mode and secure the building?:Yes|No Thanks.” The smartphone receives a user input selecting Yes or NoThanks and performs the next procedure selected by the user. If Yes isselected, the smartphone transmits the corresponding information to thewireless charger. The smartphone and the wireless charger may at leastrecognize a user pattern and recommend the user to lock doors andwindows, turn off lights, or set an alarm.

Herein, ‘profile’ is newly defined as an indicator/reference forrepresenting/indicating compatibility. In other words, when wirelesspower transmitters and receivers have the same profile, compatibilitymay be maintained therebetween so that stable power transmission andreception may be allowed. When wireless power transmitters and receivershave different profiles, stable power transmission and reception may notbe allowed. The profile may be defined according to compatibility and/orapplications regardless of (or independently of) PCs.

For example, profiles may be divided into three categories: i) Mobileand Computing, ii) Power Tool, and iii) Kitchen.

Alternatively, the profiles may be divided into four categories: i)Mobile, ii) Power Tool, iii) Kitchen, and iv) Wearable.

In the ‘Mobile’ profile, the PC may be PC0 and/or PC1. The communicationprotocol/scheme may be IB and OB, and the operating frequency may befrom 87 kHz to 205 kHz. Applications may include smartphones, laptopcomputers, and so on.

In the ‘Power Tool’ profile, the PC may be PC1. The communicationprotocol/scheme may be IB, and the operating frequency may be from 87kHz to 145 kHz. Applications may include power tools.

In the ‘Kitchen’ profile, the PC may be PC2. The communicationprotocol/scheme may be based on NFC, and the operating frequency may beless than 100 kHz. Applications may include kitchen or home appliances.

In the ‘Power Tool and Kitchen’ profiles, NFC communication may beemployed between the wireless power transmitter and receiver. Thewireless power transmitter and receiver may confirm that each of them isan NFC device by exchanging a WPC NFC data exchange profile format(NDEF). For example, as shown in FIG. 3B, the WPC NDEF may include anapplication profile field (e.g., IB), a version field (e.g., IB), andprofile-specific data (e.g., IB). The application profile fieldindicates whether the corresponding device is one of the followingprofiles: i) Mobile and Computing, ii) Power Tool, and iii) Kitchen. Theupper nibble of the version field indicates the major version, and thelower nibble of the version field indicates the minor version. Also, theprofile specific data defines contents for kitchen.

In the ‘Wearable’ profile, the PC may be PC-1. The communicationprotocol/scheme may be IB, and the operating frequency may be from 87kHz to 205 kHz. Applications may include wearable devices worn on thebody of a user.

Maintaining compatibility within the same profile may be mandatory, butmaintaining compatibility between different profiles may be optional.

The above-described profiles (Mobile profile, Power Tool profile,Kitchen profile, and Wearable profile) may be generalized to first ton-th profiles, and new profiles may be added to/substituted for oldprofiles according to WPC specifications and embodiments.

When profiles are defined as described above, a wireless powertransmitter may perform power transmission selectively only to awireless power receiver with the same profile as the wireless powertransmitter, thereby enabling more stable power transmission. Inaddition, the burden on a wireless power transmitter may be reduced, andpower transmission to incompatible wireless power receivers may notattempted, thereby preventing the wireless power transmitter fromdamaging wireless power receivers.

PC1 of the ‘Mobile’ profile may be defined by employing an optionalextension such as OB based on PC0. PC1 of the ‘Power Tool’ profile maybe defined simply as a modified version of PC1 of the ‘Mobile’ profile.The wireless transfer technology has been developed to maintaincompatibility within the same profile until now. However, in the future,the wireless transfer technology may be further developed to maintaincompatibility between different profiles. The wireless power transmitteror receiver may inform its profile to a peer device in various ways.

In the AFA standard, a wireless power transmitter is referred to as apower transmitting unit (PTU), and a wireless power receiver is referredto as a power receiving unit (PRU). PTUs are classified into a pluralityof classes as shown in Table 1, and PRUs are classified into a pluralityof categories as shown in Table 2.

TABLE 1 Minimum category Minimum value for support maximum numberP_(TX)_IN_MAX requirement of supported devices Class 1 2 W l × Category1 l × Category 1 Class 2 10 W l × Category 3 2 × Category 2 Class 3 16 Wl × Category 4 2 × Category 3 Class 4 33 W l × Category 5 3 × Category 3Class 5 50 W l × Category 6 4 × Category 3 Class 6 70 W l × Category 7 5× Category 3

TABLE 2 PRU P_(RX)_OUT_MAX Exemplary application Category 1 TBDBluetooth headset Category 2 3.5 W Feature phone Category 3 6.5 WSmartphone Category 4 13 W Tablet PC and Phablet Category 5 25 W Laptopwith a small form factor Category 6 37.5 W Regular laptop Category 7 50W Home appliance

As shown in Table 1, the maximum output power capability of a PTU ofclass n is larger than or equal to the value of P TX_IN_MAX of thecorresponding class. A PRU is not allowed to draw larger power thanspecified in the corresponding category.

FIG. 4A is a block diagram illustrating a wireless power transmissionsystem according to another embodiment of the present disclosure.

Referring to FIG. 4A, a wireless power transfer system 10 includes amobile device 450 configured to receive power wirelessly and a basestation 400 configured to transmit power wirelessly.

The base station 400 may provide inductive or resonant power and includeat least one wireless power transmitter 100 and a system unit 405. Thewireless power transmitter 100 may transmit the inductive or resonantpower and control transmission. The wireless power transmitter 100 mayinclude: a power conversion unit 110 configured to convert electricenergy to a power signal by generating a magnetic field based on primarycoil(s); and a communication and control unit 120 configured to controlcommunication with the wireless power receiver 200 and powertransmission to transmit an appropriate amount of power. The system unit405 may control operations of the base station 400 such as input powerprovisioning, control of a plurality of wireless power transmitters, andcontrol of a user interface.

The primary coil may generate an electromagnetic field based onalternating current (AC) power (voltage or current). The primary coilmay receive AC power (voltage or current) at a specific frequency outputfrom the power conversion unit 110 and generate a magnetic field at thespecific frequency. The magnetic field may be generated in a non-radialor radial form. The wireless power receiver 200 may receive the magneticfield to generate a current. In other words, the primary coil maytransmit power wirelessly.

For magnetic induction, primary and secondary coils may have arbitrarilysuitable shapes. For example, such a coil may be implemented by windinga copper wire around a high permeability member such as ferrite oramorphous metal. The primary coil may also be called a primary core,primary winding, or primary loop antenna. Meanwhile, the secondary coilmay be called a secondary core, secondary winding, secondary loopantenna, or pickup antenna.

When magnetic resonance is used, the primary and secondary coils may beprovided as a primary resonant antenna and a secondary resonant antenna.A resonant antenna may have a resonance structure including a coil and acapacitor. The resonant frequency of the resonant antenna may bedetermined by the inductance of the coil and the capacitance of thecapacitor. Here, the coil may be formed to have a loop shape. Inaddition, a core may be disposed inside the loop. The core may include aphysical core such as a ferrite core or an air core.

Energy transfer between the primary resonant antenna and the secondaryresonant antenna may be achieved by resonance in a magnetic field. Theresonance is a phenomenon in which high efficiency energy transferoccurs between two resonant antennas when the two resonant antennas arecoupled to each other. Specifically, when one of the two resonantantennas generates a near field at a resonant frequency and the otherresonant antenna is located in the vicinity thereof, the two resonantantennas may be coupled so that high efficiency energy transfer mayoccur therebetween. If a magnetic field is generated at the resonantfrequency between the primary and secondary resonant antennas, theprimary and secondary resonant antennas may resonate to each other.Thus, the magnetic field may be radiated to the secondary resonantantenna with high efficiency compared to when the magnetic fieldgenerated by the primary resonant antenna is radiated into the freespace so that energy may be transferred from the primary resonantantenna to the secondary resonant antenna with high efficiency. Themagnetic induction method may be implemented in a similar way to themagnetic resonance. However, in this case, the frequency of the magneticfield does not need to be the resonant frequency. Instead, for themagnetic induction, the loops of the primary and secondary coils need tomatch with each other, and the distance between the loops needs to bevery short.

Although not shown in the drawing, the wireless power transmitter 100may further include a communication antenna. The communication antennamay transmit and receive a communication signal on a communicationcarrier in addition to magnetic field communication. For example, thecommunication antenna may transmit and receive a communication signalbased on WiFi, Bluetooth, BLE, ZigBee, NFC, and so on.

The communication and control unit 120 may transmit and receiveinformation to and from the wireless power receiver 200. Thecommunication and control unit 120 may include at least one of an IBcommunication module or an OB communication module.

The IB communication module may transmit and receive information basedon a magnetic wave having a specific frequency as the center frequency.For example, the communication and control unit 120 may perform IBcommunication by loading information on a magnetic wave and transmittingthe magnetic wave through the primary coil or by receiving a magneticwave containing information through the primary coil. In this case, amodulation scheme such as binary phase shift keying (BPSK) or amplitudeshift keying (ASK) and a coding scheme such as Manchester coding ornon-return-to-zero level (NZR-L) coding may be used to load informationon magnetic waves or interpret information contained in magnetic waves.When the IB communication is applied, the communication and control unit120 may transmit and receive information up to a distance of severalmeters at a data rate of several kbps.

The OB communication module may perform OB communication through thecommunication antenna. For example, the communication and control unit120 may be provided as a short-range communication module. For example,the short-range communication module may include communication modulesbased on Wi-Fi, Bluetooth, BLE, ZigBee, NFC, and so on.

The communication and control unit 120 may control overall operations ofthe wireless power transmitter 100. The communication and control unit120 may compute and process various information and control each elementof the wireless power transmitter 100.

The communication and control unit 120 may be implemented as a computeror a device similar to the computer based on hardware, software, orcombination thereof. For hardware implementation, the communication andcontrol unit 120 may be provided as an electronic circuit for processingelectric signals and performing control functions. For softwareimplementation, the communication and control unit 120 may be providedas a program for driving the hardware of the communication and controlunit 120.

The communication and control unit 120 may control transmission power bycontrolling an operating point. The operating point to be controlled maycorrespond to a combination of a frequency (or phase), duty cycle, dutyratio, and voltage amplitude. The communication and control unit 120 maycontrol transmission power by adjusting at least one of the frequency(or phase), duty cycle, duty ratio, or voltage amplitude. In addition,the wireless power receiver 200 may control reception power bycontrolling the resonant frequency while the transmitter 100 suppliesconstant power.

The mobile device 450 may include the wireless power receiver 200configured to receive wireless power through the secondary coil and aload 455 configured to receive and store the power received by thewireless power receiver 200 and supply the stored power to devices.

The wireless power receiver 200 may include a power pick-up unit 210 anda communication and control unit 220. The power pick-up unit 210 mayreceive wireless power through the secondary coil and convert thereceived wireless power to electric energy. The power pick-up unit 210may rectify an AC signal obtained from the secondary coil to convert toa direct current (DC) signal. The communication and control unit 220 maycontrol transmission and reception of wireless power (power transmissionand reception).

The secondary coil may receive wireless power transmitted from thewireless power transmitter 100. The secondary coil may receive powerbased on a magnetic field generated by the primary coil. In this case,if the specific frequency is the resonant frequency, the magneticresonance may be generated between the primary and secondary coils, andthus the secondary coil may receive power more efficiently.

Although not shown in FIG. 4A, the communication and control unit 220may further include a communication antenna. The communication antennamay transmit and receive a communication signal on a communicationcarrier in addition to magnetic field communication. For example, thecommunication antenna may transmit and receive a communication signalbased on WiFi, Bluetooth, BLE, ZigBee, NFC, and so on.

The communication and control unit 220 may transmit and receiveinformation to and from the wireless power receiver 100. Thecommunication and control unit 220 may include at least one of an IBcommunication module or an OB communication module.

The IB communication module may transmit and receive information basedon a magnetic wave having a specific frequency as the center frequency.For example, the communication and control unit 220 may perform IBcommunication by loading information on a magnetic wave and transmittingthe magnetic wave through the primary coil or by receiving a magneticwave containing information through the primary coil. In this case, amodulation scheme such as BPSK or ASK and a coding scheme such asManchester coding or NZR-L coding may be used to load information onmagnetic waves or interpret information contained in magnetic waves.When the IB communication is applied, the communication and control unit220 may transmit and receive information up to a distance of severalmeters at a data rate of several kbps.

The OB communication module may perform OB communication through thecommunication antenna. For example, the communication and control unit220 may be provided as a short-range communication module.

For example, the short-range communication module may includecommunication modules based on Wi-Fi, Bluetooth, BLE, ZigBee, NFC, andso on.

The communication and control unit 220 may control overall operations ofthe wireless power transmitter 200. The communication and control unit220 may compute and process various information and control each elementof the wireless power transmitter 200.

The communication and control unit 220 may be implemented as a computeror a device similar to the computer based on hardware, software, orcombination thereof. For hardware implementation, the communication andcontrol unit 220 may be provided as an electronic circuit for processingelectric signals and performing control functions. For softwareimplementation, the communication and control unit 220 may be providedas a program for driving the hardware of the communication and controlunit 220.

When the OB communication modules or short-range communication modulesof the communication and control unit 120 and the communication andcontrol unit 220 employ Bluetooth or BLE, the communication and controlunit 120 and the communication and control unit 220 may have acommunication architecture as shown in FIG. 4B.

FIG. 4B is a diagram illustrating an exemplary Bluetooth communicationarchitecture to which the present disclosure is applicable.

Referring to FIG. 4B, (a) shows an exemplary Bluetooth basic rate(BR)/enhanced data rate (EDR) protocol stack supporting a genericattribute profile (GATT), and (b) shows an exemplary BLE protocol stack.

Specifically, as shown in (a) of FIG. 4B, the Bluetooth BR/EDR protocolstack may include an upper control stack 460 and a lower host stack 470with respect to a host controller interface (HCI) 18.

The host stack (or host module) 470 refers to hardware for transmittingor receiving a Bluetooth packet to or from a wirelesstransmission/reception module configured to receive a Bluetooth signalof 2.4 GHz. The controller stack 460 may be connected to the Bluetoothmodule to control operations of the Bluetooth module.

The host stack 470 may include a BR/EDR physical (PHY) layer 12, aBR/EDR baseband layer 14, and a link manager layer 16.

The BR/EDR PHY layer 12 may transmit and receive a 2.4 GHz radio signal.When Gaussian frequency shift keying (GFSK) modulation is used, theBR/EDR PHY layer 12 may transmit data by hopping 79 RF channels.

The BR/EDR baseband layer 14 may transmit a digital signal, select achannel sequence for hopping 1400 times per second, and transmit a timeslot with a length of 625 us for each channel.

The link manager layer 16 may control overall operations (e.g., linksetup, control, security) of Bluetooth connection based on a linkmanager protocol (LMP).

The link manager layer 16 may perform the following functions.

-   -   ACL/SCO logical transport, logical link setup, and control    -   Detach: if connection is disconnected, the link manager layer 16        may inform a peer device of a reason for the disconnection.    -   Power control and role switch    -   Security (authentication, pairing, encryption, etc.)

The host controller interface layer 18 may provide an interface betweena host module and a controller module so that the host may providecommands and data to the controller and the controller may provideevents and data to the host.

The host stack (or host module) 470 may include a logical link controland adaptation protocol (L2CAP) 21, an attribute protocol 22, a GATT 23,a generic access profile (GAP) 24, and a BR/EDR profile 25.

The L2CAP 21 may provide one two-way channel for transmitting data to aspecific protocol or profile.

The L2CAP 21 may multiplex various protocols, profiles, and so onprovided from Bluetooth.

The L2CAP of the Bluetooth BR/EDR may use dynamic channels. In addition,the L2CAP of the Bluetooth BR/EDR may support protocol servicemultiplexers, retransmission, streaming modes and provide segmentationand reassembly, per-channel flow control, and error control.

The GATT 23 may act as a protocol for explaining how the attributeprotocol 22 is used when services are configured. For example, the GATT23 may act to specify how the attributes of the attribute protocol (ATT)are grouped together into services and also act to describe featuresrelated to the services.

Accordingly, the GATT 23 and the ATT 22 may use features to describe thestates and services of a device and explain how the features are relatedto each other and how the features are used.

The ATT 22 and the BR/EDR profile 25 may define a service (profile)using the Bluetooth BR/EDR and an application protocol for exchangingdata. The GAP 24 may define device discovery, connectivity, andsecurity.

As shown in (b) of FIG. 4B, the BLE protocol stack includes a controllerstack 480 configured to process a wireless device interface where timingis important and a host stack 490 configured to process high level data.

To implement the controller stack 480, a communication module includinga Bluetooth wireless device and a processor module including aprocessing device such as a microprocessor may be used.

The host stack 490 may be implemented as part of an OS operated on theprocessor module or implemented as instantiation of a package on the OS.

In some examples, the controller stack and the host stack may beoperated or executed on the same processing device within the processormodule.

The controller stack 480 may include a PHY layer 32, link layer 34, anda HCI 36.

The PHY layer (wireless transceiver module) 32 is a layer fortransmitting and receiving a 2.4 GHz wireless signal. The PHY layer mayuses GFSK modulation and frequency hopping including 40 RF channels.

The link layer 34 may serve to transmit or receive a Bluetooth packet.Specifically, the link layer 34 may perform advertising and scanning onthree advertising channels, generate connection between devices, andexchange a data packet of up to 257 bytes over 37 data channels.

The host stack 490 may include a GAP 40, a L2CAP 41, a security manager(SM) 42, an ATT 43, a GATT 44, a GAP 25, and an LE profile 46. However,the host stack 490 is not limited thereto and may further includevarious protocols and profiles.

The host stack may multiplex various protocols, profiles, and so onprovided from Bluetooth based on L2CAP.

The L2CAP 41 may provide one two-way channel for transmitting data to aspecific protocol or profile.

The L2CAP 41 may be configured to multiplex data between higher layerprotocols, segment and reassemble packages, and manage multicast datatransmission.

In BLE, three fixed channels are basically used (one is used for CHsignaling, another is used for the SM, and the other is used for theATT). If necessary, a dynamic channel may also be used.

For the BR/EDR, a dynamic channel may be basically used. A protocolservice multiplexer, retransmission, streaming mode, and so on may besupported.

The SM 42 is a protocol for authenticating devices and providing keydistribution.

The ATT 43 may define a rule for accessing data of a peer device basedon a server-client structure. The ATT has the following 6 message types:Request, Response, Command, Notification, Indication, and Confirmation.

{circle around (1)} Request and Response messages: The request messageis a message for a client device to request specific information from aserver device. The response message is a response to the requestmessage, which is transmitted from the server device to the clientdevice.

{circle around (2)} Command message: The command message is a messagetransmitted from the client device to the server device to instruct aspecific operation. The server device sends no response to the commandmessage to the client device.

{circle around (3)} Notification message: The Notification message is amessage transmitted from the server device to the client device tonotify an event. The client device sends no confirmation message to thenotification message to the server device.

{circle around (4)} Indication and Confirmation messages: The indicationmessage is a message transmitted from the server device to the clientdevice to notify an event. However, unlike the Notification message, theclient device transmits the Confirmation message for the Indicationmessage to the server device

According to the present disclosure, when long data is requested, theGATT using the ATT 43 may let a client to know the length of data bysending the data length and receive a characteristic value from a serverbased on a universal unique identifier (UUID).

The GAP 45 is a newly implemented layer for BLE technology. The GAP 45may be used to select a role for communication between BLE devices andcontrol the occurrence of multi-profile operation.

In addition, the GAP 45 is mainly used for device discovery, connectioncreation, and security procedures. The GAP 45 may define a method forproviding information to a user, and also define the following attributetypes.

{circle around (1)} Service: It defines the basic operation of a devicebased on a combination of data related behaviors.

{circle around (2)} Include: It defines a relationship between services.

{circle around (3)} Characteristics: It is a data value used for aservice.

{circle around (4)} Behavior: It is a format readable by a computerdefined by a UUID (value type).

The LE profile 46 includes profiles dependent on the GATT. The LEprofile 46 may be mainly applied to BLE devices. The LE profile 46 mayinclude, for example, Battery, Time, FindMe, Proximity, Time, ObjectDelivery Service, and so on. Details of the GATT-based profiles are asfollows.

{circle around (1)} Battery: Battery information exchange

{circle around (2)} Time: Time information exchange

{circle around (3)} FindMe: Provision of alarm service according todistance

{circle around (4)} Proximity: Battery information exchange

{circle around (5)} Time: Time information exchange

The GATT 44 may act as a protocol for explaining how the ATT 43 is usedwhen services are configured. For example, the GATT 44 may act to definehow ATT attributes are grouped together with services and operate todescribe features associated with services. For example, the GATT 44 mayact to specify how the attributes of the ATT are grouped together intoservices and also act to describe features related to the services.

Accordingly, the GATT 44 and the ATT 43 may use features to describe thestates and services of a device and explain how the features are relatedto each other and how the features are used.

Hereinafter, procedures for the BLE technology will be brieflydescribed.

The BLE procedures may be classified into a device filtering procedure,an advertising procedure, a scanning procedure, a discovering procedure,and a connecting procedure.

Device Filtering Procedure

The device filtering procedure corresponds to a method of reducing thenumber of devices that respond to a request, an indication, anotification, etc. in the controller stack.

When requests are received from all the devices, it is unnecessary torespond thereto. Thus, the controller stack may reduce the number oftransmitted requests to reduce power consumption in the BLT controllerstack.

An advertisement device or a scanning device may perform the devicefiltering procedure to limit devices that will receive an advertisementpacket, a scan request, or a connection request.

Here, the advertising device refers to a device transmitting anadvertising event, i.e., a device performing advertising. Theadvertising device may be referred to as an advertiser.

The scanning device refers to a device performing scanning, i.e., adevice transmitting a scan request.

In BLE, when the scanning device receives some advertisement packetsfrom the advertising device, the scanning device needs to transmit ascan request to the advertisement device.

However, if the device filtering procedure is used so that scan requesttransmission is not required, the scanning device may disregard theadvertising packets transmitted from the advertising device.

The device filtering procedure may also be used for a connection requestprocedure. If device filtering is used in the connection requestprocedure, it is not necessary to transmit a response to the connectionrequest by ignoring the connection request.

Advertising Procedure

The advertising device performs the advertising procedure to performundirected broadcast to devices in an area.

Here, the undirected broadcast (undirected advertising) is advertisingdirected to all devices rather than broadcast directed to a specificdevice. All devices may scan the advertising and make an additionalinformation request or a connection request.

However, in directed broadcast (directed advertising), only a devicedesignated as the receiving device may scan advertising and make anadditional information request or a connection request.

The advertising procedure may be used to establish a Bluetoothconnection with a nearby initiating device.

Alternatively, the advertising procedure may be used to provide periodicbroadcast of user data to scanning devices that are listening on anadvertising channel.

In the advertising procedure, all advertisements (or advertising events)are broadcast on an advertising physical channel.

The advertising device may receive a scan request from a listeningdevice that are listening to obtain additional user data from theadvertising device. The advertising device transmits a response to thescan request to the device, which transmits the scan request, over thesame advertising physical channel as the advertising physical channel onwhich the scan request is received.

Broadcast user data, which is sent as part of advertisement packets, isdynamic data, whereas scan response data is generally static data.

The advertising device may receive a connection request from theinitiating device on the advertising (broadcast) physical channel. Ifthe advertising device uses a connectable advertising event and theinitiating device is not filtered by the device filtering procedure, theadvertising device may stop advertising and enter a connected mode. Theadvertising device may start advertising again after the connected mode.

Scanning Procedure

The scanning device, that is, a device that performs scanning performsthe scanning procedure to listen to undirected broadcast of user datafrom advertising devices using advertising physical channels.

The scanning device transmits a scan request to the advertising deviceover the advertising physical channel to request additional data fromthe advertising device. The advertising device transmits a scanresponse, which is a response to the scan request, including additionaldata requested by the scanning device on the advertising physicalchannel.

The scanning device may use the scanning procedure while establishingconnection with another BLE device in the BLE piconet.

If the scanning device receives a broadcast advertising event and is inan initiator mode capable of initiating a connection request, thescanning device may transmit the connection request to the advertisingdevice over the advertising physical channel in order to initiate aBluetooth connection with the advertising device.

When the scanning device sends the connection request to the advertisingdevice, the scanning device may stop the initiator mode scanning foradditional broadcast and enter the connected mode.

Discovering Procedure

Devices capable of Bluetooth communication (hereinafter referred to asBluetooth devices) may perform the advertising procedure and scanningprocedure to discover nearby devices or to be discovered by otherdevices within a given area.

The discovery procedure is performed asymmetrically. A Bluetooth deviceattempting to discover other nearby devices is called a discoveringdevice. The discovering device listens to discover devices thatadvertise a scannable advertising event. An available Bluetooth devicediscovered by other devices is called a discoverable device. Thediscoverable device actively broadcasts an advertising event over theadvertisement (broadcast) physical channel so that other devices scanthe advertising event.

Both the discovering device and discoverable device may be alreadyconnected to other Bluetooth devices in the piconet.

Connecting Procedure

The connecting procedure is asymmetric. For the connecting procedure, itis required that other Bluetooth devices perform the scanning procedurewhile a specific Bluetooth device performs the advertising procedure.

That is, the advertising procedure may be the goal, so that only onedevice will respond to advertising. After receiving an accessibleadvertising event from the advertising device, the device may initiateconnection by sending a connection request to the advertising deviceover the advertising (broadcast) physical channel.

Hereinafter, operation states in the BLE technology such as anadvertising state, a scanning state, an initiating state, and aconnection state will be briefly reviewed.

Advertising State

The link layer (LL) enters the advertising state according to aninstruction from the host (stack). When the LL is in the advertisingstate, the LL transmits advertising packet data units (PDUs) foradvertising events.

Each advertising event may include at least one advertisement PDU, andthe advertising PDUs may be transmitted by advertising channel indicesin use. The advertising event may be terminated when the advertisingevent is transmitted by the advertising channel indices where theadvertising PDU(s) are used. If the advertising device needs to reservea space for performing other functions, the advertising event may beterminated earlier.

Scanning State

The LL enters the scanning state according to an instruction from thehost (stack). In the scanning state, the LL listens to advertisingchannel indices.

The scanning state has two types: passive scanning and active scanning.Each scanning type is determined by the host.

A separate time or advertising channel index for performing scanning isnot defined.

In the scanning state, the LL listens to an advertising channel indexfor a scan window (scanWindow) duration. A scan interval (scanInterval)is defined as the interval between the starting points of twoconsecutive scan windows.

If there is no collision in scheduling, the LL should complete all scanintervals of scan windows as instructed by the host. In each scanwindow, the LL should scan a different advertising channel index. The LLuses every available advertising channel index.

For passive scanning, the LL only receives packets and does not transmitany packets.

For active scanning, the LL performs listening to receive an advertisingPDU type for requesting advertising PDUs and additional informationrelated to the advertising device from the advertising device.

Initiating State

The LL enters the initiating state according to an instruction from thehost (stack).

When the LL is in the initiating state, the LL listens to advertisingchannel indices.

In the initiating state, the LL listens to an advertising channel indexfor a scan window duration.

Connection State

The LL enters the connection state when the initiating device, i.e., adevice performing a connection request transmits a CONNECT_REQ PDU tothe advertising device or when the advertising device receives theCONNECT_REQ PDU from the initiating device.

After the LL enters the connection state, connection may be created.However, the connection may not need to be established when the LLenters the connection state. The only difference between a newly createdconnection and a previously established connection is an LL connectionsupervision timeout value.

When two devices are connected, the two devices perform different roles.

An LL performing a master role is called a master, and an LL performinga slave role is called a slave. The master controls the timing of aconnection event, and the connection event refers to a synchronizationtime point between the master and the slave.

Hereinafter, packets defined for a Bluetooth interface will be describedin brief. BLE devices use the following packets.

Packet Format

The LL has only one packet format used for both an advertising channelpacket and data channel packet.

Each packet includes four fields: a preamble field, an access addressfield, a PDU field, and a CRC field.

When one packet is transmitted on an advertising channel, the PDU may bean advertising channel PDU, and when one packet is transmitted on a datachannel, the PDU may be a data channel PDU.

Advertising Channel PDU

The advertising channel PDU has a 16-bit header and a payload of varioussizes.

The PDU type field of the advertising channel PDU included in the headerindicates PDU types defined in Table 3 below.

TABLE 3 PDU Type Packet Name 0000 ADV_IND 0001 ADV_DIRECT_IND 0010ADV_NONCONN_IND 0011 SCAN_REQ 0100 SCAN_RSP 0101 CONNECT_REQ 0110ADV_SCAN_IND 0111-1111 Reserved

Advertising PDU

The following advertising channel PDU types are called the advertisingPDU and used in specific events.

ADV_IND: Connectable undirected advertising event

ADV_DIRECT_IND: Connectable directed advertising event

ADV_NONCONN_IND: Non-connectable undirected advertising event

ADV_SCAN_IND: Scannable undirected advertising event

The PDUs are transmitted by the LL in the advertising state and arereceived by the LL in the scanning state or initiating state.

Scanning PDU

The following advertising channel PDU types are called the scanning PDUand used in states described below.

SCAN_REQ: SCAN_REQ is transmitted by the LL in the scanning state andreceived by the LL in the advertising state.

SCAN_RSP: SCAN_RSP is transmitted by the LL in the advertising state andreceived by the LL in the scanning state.

Initiating PDU

The following advertising channel PDU type is called the initiating PDU.

CONNECT_REQ: CONNECT_REQ is transmitted by the LL in the initiatingstate and received by the LL in the advertising state.

Data Channel PDU

The data channel PDU has a 16-bit header and a payload of various sizes.The data channel PDU may include a message integrity check (MIC) field.

The procedures, states, packet formats, etc. in the BLE technologydiscussed above may be applied to perform methods proposed in thepresent disclosure.

Referring again to FIG. 4A, the load 455 may be a battery. The batterymay store energy based on power outputted from the power pick-up unit210. The mobile device 450 may not mandatorily include the battery. Forexample, the battery may be provided as a detachable external component.In another example, the wireless power receiver 200 may include adriving means for performing various operations of the electronicdevice, instead of the battery.

Although it is shown that the mobile device 450 includes the wirelesspower receiver 200 and the base station 400 includes the wireless powertransmitter 100, the wireless power receiver 200 may be identified withthe mobile device 450 and the wireless power transmitter 100 may beidentified with the base station 400 in a broad sense.

When the communication and control unit 120 and the communication andcontrol unit 220 include Bluetooth or BLE as the OB communication moduleor short-range communication module in addition to the IB communicationmodule, the wireless power transmitter 100 including the communicationand control unit 120 and the wireless power receiver 200 including thecommunication and control unit 220 may be illustrated as a simple blockdiagram such as FIG. 4C.

FIG. 4C is a block diagram illustrating a wireless power transfer systemusing BLE communication according to an embodiment of the presentdisclosure.

Referring to FIG. 4C, the wireless power transmitter 100 includes thepower conversion unit 110 and the communication and control unit 120.The communication and control unit 120 includes an in-band communicationmodule 121 and a BLE communication module 122.

The wireless power receiver 200 includes the power pickup unit 210 andthe communication and control unit 220. The communication and controlunit 220 includes an in-band communication module 221 and a BLEcommunication module 222.

In one aspect, the BLE communication modules 122 and 222 perform thearchitectures and operations shown in FIG. 4B. For example, the BLEcommunication modules 122 and 222 may be used to establish connectionbetween the wireless power transmitter 100 and the wireless powerreceiver 200 and exchange control information and packets necessary forwireless power transfer.

In another aspect, the communication and control unit 120 may beconfigured to operate a profile for wireless charging. Here, the profilefor wireless charging may be a GATT based on BLE transmission.

As shown in FIG. 4D, the communication and control units 120 and 220include only the in-band communication modules 121 and 221,respectively. The BLE communication modules 122 and 222 may be providedseparately from the communication and control units 120 and 220.

Hereinafter, a coil or coil unit may be referred to as a coil assembly,a coil cell, or a cell, which includes the coil and at least one elementclose to the coil.

FIG. 5 is a state transition diagram for explaining a wireless powertransfer procedure.

Referring to FIG. 5, power transfer from the wireless power transmitterto the wireless power receiver according to an embodiment of the presentdisclosure may be broadly divided into a selection phase 510, a pingphase 520, an identification and configuration phase 530, a negotiationphase 540, a calibration phase 550, a power transfer phase 560, and arenegotiation phase 570.

The selection phase 510 is a transition phase including referencenumerals S502, S504, S508, S510, and S512 when a specific error or aspecific event is detected at the beginning of or during power transfer.The specific error and specific event will be described in detail later.In the selection phase 510, the wireless power transmitter may monitorwhether an object is present on an interface surface. If the wirelesspower transmitter detects that an object is placed on the interfacesurface, the wireless power transmitter may transition to the ping phase520. In the selection phase 510, the wireless power transmittertransmits an analog ping signal, which is a power (or pulse) signal witha very short duration. The wireless power transmitter may detect whetheran object is present in an active area of the interface surface based ona current change in a transmitting coil or a primary coil.

When an object is detected in the selection phase 510, the wirelesspower transmitter may measure the quality factor of a wireless powerresonance circuit (e.g., a power transmission coil and/or a resonancecapacitor). According to an embodiment of the present disclosure, whenan object is detected in the selection phase 510, the wireless powertransmitter may measure the quality factor to determine whether aforeign object exists in the charging area along with the wireless powerreceiver. The inductance and/or series resistance component of the coilprovided in the wireless power transmitter may be reduced due to achange in the environment, and the decrease may reduce the qualityfactor. To determine the presence or absence of a foreign object basedon the measured quality factor, the wireless power transmitter mayreceive from the wireless power receiver a reference quality factor,which is measured in advance in a state where no foreign object isplaced in the charging area. The wireless power transmitter maydetermine the presence or absence of a foreign object by comparing themeasured quality factor with the reference quality factor, which isreceived during the negotiation phase 540. However, when the wirelesspower receiver has a low reference quality factor (for example, thereference quality factor of the wireless power receiver may decreasedepending on the type, purpose, characteristics, etc. of the wirelesspower receiver), the difference between the reference quality factor andthe quality factor measured under the presence of a foreign object maybe insignificant so that it may be difficult to determine the presenceof the foreign object. Accordingly, in this case, other determinationfactors should be further considered, or the presence of a foreignobject should be determined based on another method.

In another embodiment of the present disclosure, when an object isdetected in the selection phase 510, the quality factor may be measuredwithin a specific frequency range (e.g., operating frequency range) todetermine whether the object is placed with a foreign object in thecharging area. The inductance and/or series resistance component of thecoil of the wireless power transmitter may be reduced due to a change inthe environmental, and thus the resonant frequency of the coil of thewireless power transmitter may be changed (shifted). That is, a qualityfactor peak frequency, which is a frequency at which the maximum qualityfactor is measured within the operating frequency band, may be shifted.

In the ping phase 520, if the wireless power transmitter detects anobject, the wireless power transmitter wakes up the receiver andtransmits a digital ping for identifying whether the detected object isthe wireless power receiver. If the wireless power transmitter fails toreceive a response signal for the digital ping such as a signalintensity packet from the receiver during the ping phase 520, thewireless power transmitter may transition back to the selection phase510. In addition, if the wireless power transmitter receives a signalindicating the completion of the power transfer such as a chargingcomplete packet from the receiver during the ping phase 520, thewireless power transmitter may transition back to the selection phase510.

When the ping phase 520 is completed, the wireless power transmitter maytransition to the identification and configuration phase 530 foridentifying the receiver and collecting information on the configurationand state of the receiver.

During the identification and configuration phase 530, if the wirelesspower transmitter receives an unexpected packet or fails to receive adesired packet for a predetermined period of time, if a packettransmission error occurs, or if no power transfer contract isconfigured, the wireless power transmitter may transition to theselection phase 510.

Based on the value of a negotiation field in a configuration packet,which is received during the identification and configuration phase 530,the wireless power transmitter may check whether the wireless powertransmitter needs to enter the negotiation phase 540. If negotiation isneeded, the wireless power transmitter may enter the negotiation phase540 and then perform a predetermined a foreign object detection (FOD)detection procedure. On the contrary, if no negotiation is needed, thewireless power transmitter may immediately enter the power transferphase 560.

In the negotiation phase 540, the wireless power transmitter may receivea FOD status packet including the reference quality factor.Alternatively, the wireless power transmitter may receive an FOD statuspacket including a reference peak frequency. Alternatively, the wirelesspower transmitter may receive an FOD status packet including thereference quality factor and the reference peak frequency. In this case,the wireless power transmitter may determine a quality factor thresholdfor FOD based on the reference quality factor. The wireless powertransmitter may determine a peak frequency threshold for FOD based onthe reference peak frequency value.

The wireless power transmitter may detect whether a foreign object (FO)exists in the charging area based on the determined quality factorthreshold for FOD and the currently measured quality factor (which ismeasured before the ping phase). The wireless power transmitter maycontrol power transfer according to the FOD result. For example, whenthe FO is detected, the wireless power transmitter may stop the powertransfer, but the present disclosure is not limited thereto.

The wireless power transmitter may detect whether an FO exists in thecharging area based on the determined peak frequency threshold for FODand the currently measured peak frequency (which is measured before theping phase). The wireless power transmitter may control power transferaccording to the FOD result. For example, when the FO is detected, thewireless power transmitter may stop the power transfer, but the presentdisclosure is not limited thereto.

When the FO is detected, the wireless power transmitter may return tothe selection phase 510. On the other hand, when the FO is not detected,the wireless power transmitter may enter the power transfer phase 560through the calibration phase 550. Specifically, when the FO is notdetected, the wireless power transmitter may determine the strength ofpower received by the receiver and then measure power loss between thereceiver and transmitter in the calibration phase 550 in order todetermine the strength of power transmitted from the transmitting end.That is, the wireless power transmitter may estimate the power lossbased on a difference between the transmitted power of the transmitterand the received power of the receiver in the calibration phase 550. Inone embodiment, the wireless power transmitter may correct the thresholdfor FOD by reflecting the estimated power loss.

During the power transfer phase 560, if the wireless power transmitterreceives an unexpected packet or fails to receive a desired packet for apredetermined period of time, if there is an error in the predeterminedpower transfer contract (power transfer contract violation), or ifcharging is completed, the wireless power transmitter may transition tothe selection phase 510.

If the wireless power transmitter needs to reconfigure the powertransfer contract according to a change in the state of the wirelesspower transmitter during the power transfer phase 560, the wirelesspower transmitter may transition to the renegotiation phase 570. In thiscase, if the renegotiation is normally completed, the wireless powertransmitter may return to the power transfer phase 560.

In this embodiment, although the calibration phase 550 and the powertransfer phase 560 are separated into different phases, the calibrationphase 550 may be integrated into the power transfer phase 560. In thiscase, the operations in the calibration phase 550 may be performedduring the power transfer phase 560.

The power transfer contract may be established based on informationabout the states and characteristics of the wireless power transmitterand receiver. For example, the wireless power transmitter stateinformation may include information on the maximum amount of transmittedpower, information on the maximum number of acceptable receivers, etc.The wireless power receiver state information may include information onrequired power, etc.

FIG. 6 illustrates a power control method according to an embodiment ofthe present disclosure.

Referring to FIG. 6, in the power transfer phase 560, the wireless powertransmitter 100 and the wireless power receiver 200 may control theamount of power transmitted for both communication and powertransmission/reception. The wireless power transmitter and wirelesspower receiver operate at a specific control point. The control pointrepresents a combination of the voltage and current provided at theoutput end of the wireless power receiver when the power transfer isperformed.

More specifically, the wireless power receiver may select a desiredcontrol point such as a desired output current/voltage and thetemperature of a specific location of the mobile device and additionallydetermine an actual control point. The wireless power receiver maycalculate a control error value based on the desired control point andthe actual control point and transmit the control error value to thewireless power transmitter as a control error packet.

In addition, the wireless power transmitter may control the powertransfer by configuring/controlling a new operating point such as anamplitude, a frequency, and a duty cycle based on the received controlerror packet. Thus, the control error packet is transmitted/received atregular time intervals during the power transfer phase. In anembodiment, the wireless power receiver may set the control error valueto a negative number to reduce the current of the wireless powertransmitter. On the contrary, the wireless power receiver may set thecontrol error value to a positive value to increase the current of thewireless power transmitter. In an induction mode, the wireless powerreceiver may control the power transfer by transmitting the controlerror packet to the wireless power transmitter as described above.

A resonance mode, which will be described below, may operate in adifferent way from the induction mode. In the resonance mode, onewireless power transmitter needs to be capable of simultaneously servinga plurality of wireless power receivers. However, when power transfer iscontrolled as in the induction mode, transmitted power may be controlledby communication with one wireless power receiver, and as a result, itmay be difficult to control power transfer to additional wireless powerreceivers. Therefore, in the resonant mode of present disclosure, thewireless power transmitter may transmit basic power in common, and thewireless power receiver may control the amount of received power bycontrolling its own resonance frequency. However, the method describedwith reference to FIG. 6 is not completely excluded even in theresonance mode operation, and additional transmission power control maybe performed according to the method of FIG. 6.

FIG. 7 is a block diagram of a wireless power transmitter according toanother embodiment of the present disclosure. The wireless powertransmitter may be included in a wireless power transfer systemoperating in a magnetic resonance mode or a shared mode. The shared modemay refer to a mode in which a wireless power transmitter performsone-to-many communication and charging with wireless power receivers.The shared mode may be implemented based on magnetic induction orresonance.

Referring to FIG. 7, a wireless power transmitter 700 may include atleast one of a cover 720 configured to cover a coil assembly, a poweradapter 730 configured to supply power to a power transmitter 740, thepower transmitter 740, or a user interface 750 configured to providepower transfer progress and other related information. In particular,the user interface 750 may be optionally included or may be included asanother user interface 750 for the wireless power transmitter 700.

The power transmitter 740 may include at least one of a coil assembly760, an impedance matching circuit 770, an inverter 780, a communicationunit 790, or a control unit 710.

The coil assembly 760 may include at least one primary coil configuredto generate a magnetic field. The coil assembly 760 may be referred toas a coil cell.

The coil assembly 760 may include at least one primary coil configuredto generate a magnetic field. The coil assembly 760 may be referred toas a coil cell. The impedance matching circuit 770 may provide impedancematching between the inverter and the primary coil(s). The impedancematching circuit 770 may generate resonance at a suitable frequency toboost the primary coil current. If the power transmitter 740 is amulti-coil power transmitter, the impedance matching circuit may furtherinclude a multiplexer configured to route a signal from the inverter toa subset of the primary coils. The impedance matching circuit may bereferred to as a tank circuit.

The impedance matching circuit 770 may include a capacitor, an inductor,and a switching device for switching connection thereof. The impedancematching may be performed as follows. First, the reflected wave ofwireless power transmitted through the coil assembly 760 is detected.Then, the switching device is switched based on the detected reflectedwave so that the connection state of the capacitor or inductor, thecapacitance of the capacitor, or the inductance of the inductor isadjusted. In some cases, the impedance matching circuit 770 may beomitted. The present disclosure may include an embodiment in which thewireless power transmitter 700 does not include the impedance matchingcircuit 770.

The inverter 780 may convert a DC input into an AC signal. The inverter780 may be a half-bridge inverter or a full-bridge inverter to generatepulse waves and duty cycles at adjustable frequencies. The inverter mayalso include a plurality of stages to adjust the input voltage level.

The communication unit 790 may perform communication with a powerreceiver. The power receiver performs load modulation to transmitrequests and information to the power transmitter. Accordingly, thepower transmitter 740 may monitor the amplitude and/or phase of thecurrent and/or voltage of the primary coil in order to demodulate datatransmitted by the power receiver based on the communication unit 790.

In addition, the power transmitter 740 may control output power totransmit data through the communication unit 790 based on frequencyshift keying (FSK).

The control unit 710 may control communication and power transmission ofthe power transmitter 740. The control unit 710 may control the powertransmission by adjusting the above-described operating point. Theoperating point may be determined by, for example, at least one of anoperating frequency, a duty cycle, and an input voltage.

The communication unit 790 and the control unit 710 may be provided asseparate units/devices/chipsets or as one unit/device/chipsets.

FIG. 8 illustrates a wireless power receiver according to anotherembodiment of the present disclosure. The wireless power receiver may beincluded in a wireless power transfer system operating in the magneticresonance mode or shared mode.

In FIG. 8, a wireless power receiving device 800 may include at leastone of a user interface 820 configured to provide power transferprogress and other related information, a power receiver 830 configuredto receives wireless power, a load circuit 840, or a base 850 configuredto support and cover a coil assembly. In particular, the user interface820 may be optionally included or may be included as another userinterface 820 of the power receiver.

The power receiver 830 may include at least one of a power converter860, an impedance matching circuit 870, a coil assembly 880, acommunication unit 890, or a control unit 810.

The power converter 860 may convert AC power received from a secondarycoil into a voltage and current suitable for the load circuit. In anembodiment, the power converter 860 may include a rectifier. Therectifier may rectify received wireless power in order to convert thereceived wireless power from AC power to DC power. The rectifier may usea diode or a transistor to convert the AC power into the DC power anduse a capacitor and a resistor to smooth the DC power. A full-waverectifier, a half-wave rectifier, a voltage multiplier, etc., which areimplemented as a bridge circuit, may be used as the rectifier.Additionally, the power converter may adapt the reflected impedance ofthe power receiver.

The impedance matching circuit 870 may provide impedance matchingbetween the secondary coil and a combination of the power converter 860and the load circuit 840. In an embodiment, the impedance matchingcircuit 870 may generate resonance at a frequency near 100 kHz toimprove power transfer. The impedance matching circuit 870 may include acapacitor, an inductor, and a switching device for switching acombination thereof. The impedance matching may be performed bycontrolling the switching device in the impedance matching circuit 870based on the voltage, current, power, frequency, etc. of the receivedwireless power. In some cases, the impedance matching circuit 870 may beomitted. The present disclosure may include an embodiment in which thewireless power transmitter 800 does not include the impedance matchingcircuit 870.

The coil assembly 880 includes at least one secondary coil. In addition,the coil assembly 880 may optionally include an element for shielding ametal part of the receiver from the magnetic field.

The communication unit 890 may perform load modulation to providerequests and other information to the power transmitter.

To this end, the power receiver 830 may switch the resistor or capacitorto change the reflected impedance.

The control unit 810 may control received power. To this end, thecontrol unit 810 may determine/calculate a difference between the actualoperating point and desired operating point of the power receiver 830.In addition, the control unit 810 may adjust/reduce the differencebetween the actual operating point and desired operating point byadjusting the reflected impedance of the power transmitter and/orperforming a request for adjusting the operating point of the powertransmitter. When the difference is minimized, optimal power receptionmay be achieved.

The communication unit 890 and the control unit 810 may be provided asseparate devices/chipsets or as one device/chipset.

FIG. 9 illustrates a communication frame structure according to anembodiment of the present disclosure. The communication frame structuremay be a communication frame structure operating in the shared mode.

Referring to FIG. 9, different types of frames may be used together inthe shared mode. For example, a slotted frame having a plurality ofslots as shown in (A) and a free-format frame having no specific shapeas shown in (B) may be used in the shared mode. Specifically, theslotted frame is a frame for transmission of short data packets from thewireless power receiver 200 to the wireless power transmitter 100, andthe free-format frame is a frame capable of transmission of long datapackets due to no slots.

Meanwhile, the slotted frame and the free-format frame may be calledvarious names by those skilled in the art. For example, the slottedframe may be referred to as a channel frame, and the free-format framemay be referred to as a message frame.

Specifically, the slotted frame may include a synchronization patternindicating the start of the frame, a measurement slot, 9 slots, andadditional synchronization patterns having the same time duration, whichare located before the 9 slots, respectively.

Here, the additional synchronization pattern is different from theabove-described synchronization pattern indicating the start of theframe. Specifically, an additional synchronization pattern may indicateinformation on adjacent slots (information on two consecutive slotslocated on the sides of the synchronization pattern), instead ofindicating the start of the frame.

The synchronization pattern may be located between two consecutive slotsamong the 9 slots. In this case, the synchronization pattern may provideinformation on the two consecutive slots.

In addition, the 9 slots and the synchronization patterns providedbefore the 9 slots may have the same time duration. For example, each ofthe 9 slots may have a time duration of 50 ms. Also, each of the 9synchronization patterns may have a time duration of 50 ms.

On the other hand, the free-format frame shown in (B) may not have aspecific form except for the synchronization pattern indicating thestart of the frame and the measurement slot. That is, the free-formatframe is to perform a different role from the slotted frame. Forexample, the free-format frame may be used for communication of longdata packets (e.g., additional owner information packets) between thewireless power transmitter and the wireless power receiver.Alternatively, when the wireless power transmitter includes a pluralityof coils, the free-format frame may be used to select any one of theplurality of coils.

Hereinafter, synchronization patterns included in each frame will bedescribed in detail with reference to the drawings.

FIG. 10 illustrates a structure of a synchronization pattern accordingto an embodiment of the present disclosure.

Referring to FIG. 10, the synchronization pattern includes a preamble, astart bit, a response field, a type field, an information field, and aparity bit. In FIG. 10, the start bit is denoted by ZERO.

Specifically, the preamble may include consecutive bits, all of whichmay be set to 0. That is, the preamble may be bits for matching the timelength of the synchronization pattern.

The number of bits included in the preamble may depend on the operatingfrequency such that the length of the synchronization pattern is closestto 50 within a range not exceeding 50 ms. For example, when theoperating frequency is 100 kHz, the synchronization pattern may includetwo preamble bits. When the operating frequency is 105 kHz, thesynchronization pattern may include three preamble bits.

The start bit may be located behind the preamble and denoted by ZERO.ZERO may indicate the type of the synchronization pattern. Here, thesynchronization pattern type may include frame synchronization includingframe related information and slot synchronization including slotrelated information. That is, the synchronization pattern may correspondto either the frame synchronization, which is located betweenconsecutive frames and indicates the start of a frame, or the slotsynchronization, which is located between consecutive slots among aplurality of slots included in a frame and includes includinginformation on the consecutive slot.

For example, if ZERO is 0, it may mean that the synchronization patternis the slot synchronization between slots. If ZERO is 1, it may meanthat the synchronization pattern is the frame synchronization locatedbetween frames.

The parity bit is the last bit of the synchronization pattern and mayindicate information on the number of bits in the data fields (i.e.,response field, type field, information field) of the synchronizationpattern. For example, when the number of bits included in the datafields of the synchronization pattern is an even number, the parity bitmay be 1. Otherwise (when the number of bits is an odd number), theparity bit may be 0.

The response field may include information on the response of thewireless power transmitter to communication with the wireless powerreceiver in a slot before the synchronization pattern. For example, theresponse field may be set to 00 if the wireless power transmitter doesnot detect communication with the wireless power receiver. The responsefield may be set to 01 if the wireless power transmitter has acommunication error in communication with the wireless power receiver.The communication error may occur when two or more wireless powerreceivers attempt to access one slot and thus a collision occurs betweenthe two or more wireless power receivers.

The response field may include information on whether a data packet iscorrectly received from the wireless power receiver. Specifically, theresponse field may be set to 10 (negative acknowledgement (NAK)) whenthe wireless power transmitter denies the data packet. The responsefield may be set to 11 (acknowledgement (ACK)) when the wireless powertransmitter confirms the data packet.

The type field may indicate the type of the synchronization pattern.Specifically, when the synchronization pattern is the firstsynchronization pattern of the frame (that is, when the synchronizationpattern is the first synchronization pattern of the frame located beforethe measurement slot), the type field may be set to 1 to indicate theframe synchronization.

When the synchronization pattern is not the first synchronizationpattern of the frame in the slotted frame, the type field may be set to0 to indicate the slot synchronization.

The value of the information field may be determined according to thesynchronization pattern type indicated by the type field. For example,when the type field is 1 (frame synchronization), the information fieldmay indicate the frame type. That is, the information field may indicatewhether the current frame is the slotted frame or free-format frame. Forexample, when the information field is 00, it may indicate the slottedframe. When the information field is 01, it may indicate the free-formatframe.

On the contrary, when the type field is 0 (slot synchronization), theinformation field may indicate the state of a next slot located afterthe synchronization pattern. Specifically, the information field may beset to 00 when the next slot is a slot allocated to a specific wirelesspower receiver. The information field may be set to 01 when the nextslot is locked for temporary use by a specific wireless power receiver.The information field may be set to 10 when the next slot is a slotfreely available to any wireless power receiver.

FIG. 11 illustrates operating states of a wireless power transmitter andreceiver in the shared mode according to an embodiment of the presentdisclosure.

Referring to FIG. 11, the wireless power receiver operating in theshared mode may be in any one of a selection phase 1100, an introductionphase 1110, a configuration phase 1120, a negotiation phase 1130, and apower transfer phase 1140.

According to an embodiment of the present disclosure, the wireless powertransmitter may transmit a wireless power signal to detect the wirelesspower receiver. That is, a process for detecting the wireless powerreceiver based on the wireless power signal may be referred to as analogping.

Upon receiving the wireless power signal, the wireless power receivermay enter the selection phase 1100. After entering the selection phase1100, the wireless power receiver may detect the presence of an FSKsignal on the wireless power signal as described above.

That is, the wireless power receiver may perform communication in eitheran exclusive mode or the shared mode depending on the presence of theFSK signal.

Specifically, if the wireless power signal includes the FSK signal, thewireless power receiver may operate in the shared mode. Otherwise, thewireless power receiver may operate in the exclusive mode.

When the wireless power receiver operates in the shared mode, thewireless power receiver may enter the introduction phase 1110. Thewireless power receiver may transmit a control information (CI) packetto the wireless power transmitter in the introduction phase 1110 inorder to transmit CI packets in the configuration phase, negotiationphase, and power transfer phase. The CI packet may include a header andcontrol related information. For example, the header in the CI packetmay be 0X53.

In the introduction phase 1110, the wireless power receiver attempts torequest free slots in order to transmit CI packets in the configuration,negotiation, and power transmission phases. The wireless power receiverselects a free slot and transmits the first CI packet. If the wirelesspower transmitter transmits an ACK for the CI packet, the wireless powertransmitter enters the configuration phase. If the wireless powertransmitter transmits a NACK, it may be interpreted to mean that anotherwireless power receiver is in the process of configuring andnegotiating. In this case, the wireless power receiver attempts torequest free slots again.

If the wireless power receiver receives the ACK in response to the CIpacket, the wireless power receiver determines the position of a privateslot in a frame by counting the remaining synchronization slots untilthe first frame synchronization. In all subsequent slot-based frames,the wireless power receiver transmits a CI packet through thecorresponding slot.

If the wireless power transmitter allows the wireless power receiver toproceed to the configuration phase, the wireless power transmitterprovides a series of locked slots for exclusive use of the wirelesspower receiver, which ensures that the wireless power receiver proceedsto the configuration phase without collision.

The wireless power receiver transmits sequences of data packets such astwo identification data packets (IDHI and IDLO) in the locked slots.After completing this step, the wireless power receiver enters thenegotiation phase. In the negotiation phase, the wireless powertransmitter continues to provide the wireless power receiver with lockedslots for exclusive use. This ensures that the wireless power receiverproceeds to the negotiation phase without collision.

The wireless power receiver transmits one or more negotiation datapackets in the corresponding locked slots, and in this case, thenegotiation data packets may be mixed with private data packets.Eventually, the sequence ends with a specific request (SRQ) packet.After completion of the sequence, the wireless power receiver enters thepower transfer phase, and the wireless power transmitter stops providinglocked slots.

In the power transfer phase, the wireless power receiver transmits a CIpacket in an allocated slot and receives power. The wireless powerreceiver may include a regulator circuit. The regulator circuit may beincluded in a communication and control unit. The wireless powerreceiver may self-regulate the reflection impedance of the wirelesspower receiver based on the regulator circuit. In other words, thewireless power receiver may adjust the reflected impedance to transmitthe amount of power required by an external load, which may preventexcessive power reception and overheating.

In the shared mode, the wireless power transmitter may not perform poweradjustment in response to the received CI packet (depending on theoperation mode), and thus, control may be required to prevent anovervoltage state.

Hereinafter, authentication between the wireless power transmitter andthe wireless power receiver will be described.

A wireless power transfer system using IB communication may employ USB-Cauthentication. The authentication includes authentication of thewireless power transmitter by the wireless power receiver andauthentication of the wireless power receiver by the wireless powertransmitter.

FIG. 12 is a block diagram illustrating a wireless charging certificateformat according to an embodiment of the present disclosure.

Referring to FIG. 12, the wireless charging certificate format mayinclude a wireless charging standard certificate structure version (QiAuthentication Certificate Structure Version), a reserved bit, a PTx andleaf indicator (PTx Leaf), a certificate type, a signature offset, aserial number, an issuer ID, a subject ID, a public key, and asignature.

In the wireless charging certificate format, the PTx and leaf indicatoris separated from the certificate type so that the PTx and leafindicator and the certificate type are allocated to different bits inthe same byte (B0).

The PTx and leaf indicator indicates not only whether the correspondingcertificate relates to the wireless power transmitter but also whetherthe corresponding certificate is a leaf certificate. That is, the PTxand leaf indicator may indicate whether the corresponding certificate isthe leaf certificate for the wireless power transmitter or not.

The PTx and leaf indicator may be 1 bit. If the PTx and leaf indicatoris 0, it may indicate that the corresponding certificate is not the leafcertificate or that the corresponding certificate is the leafcertificate of the wireless power receiver. On the other hand, if thePTx and leaf indicator is 1, it may indicate that the correspondingcertificate is the leaf certificate of the wireless power transmitter.

The certificate type is, for example, 2 bits. The certificate type mayindicate that the corresponding certificate is any one of a rootcertificate, an intermediate certificate, and a leaf certificate.Alternatively, the certificate type may indicate that the correspondingcertificate is for all of them.

The wireless power transmitter may inform the wireless power receiverwhether the authentication function is supported through a capabilitypacket (in the case of authentication of the wireless power transmitterby the wireless power receiver (authentication of PTx by PRx)).Hereinafter, the structure of indication information (capability packetand configuration packet) regarding whether or not the authenticationfunction is supported will be described in detail.

FIG. 13 illustrates a structure of a capability packet of a wirelesspower transmitter according to an embodiment of the present disclosure.

Referring to FIG. 13, a capability packet having a corresponding headervalue of 0X31 is 3 bytes. The first byte (B0) includes a power class anda guaranteed power value. The second byte (B1) includes a reserved bitand a potential power value. The third byte (B2) includes an AI (AI), anAR (AR), a reserved bit, WPID, and Not Res Sens. Specifically, the AI is1 bit. For example, if the value of the AI is ‘1b’, it indicates thatthe wireless power transmitter may operate as an AI. In addition, the ARis 1 bit. For example, if the value of the AR is ‘1b’, it indicates thatthe wireless power transmitter may operate as an AR.

FIG. 14 illustrates a structure of a configuration packet of a wirelesspower receiver according to an embodiment of the present disclosure.

Referring to FIG. 14, a configuration packet having a header value of0X51 is 5 bytes. The first byte (B0) includes a power class and amaximum power value. The second byte (B1) includes an AI, an AR, and areserved bit (Reserve). The third byte (B2) includes Prop, Reserve,ZERO, and Count. The fourth byte (B3) includes a window size and awindow offset. The fifth byte (B4) includes Neg, polarity, depth,authentication (Auth), and Reserve. Specifically, the AI is 1 bit. Forexample, if the AI value is ‘1b’, it indicates that the wireless powerreceiver may operate as an AI. In addition, the AR is 1 bit. Forexample, if the AR value is ‘1b’, it indicates that the wireless powerreceiver may operate as an AR.

A message used in an authentication procedure is called anauthentication message. The authentication message is used to carryinformation related to authentication. There are two types ofauthentication messages. One is an authentication request, and the otheris an authentication response. The authentication request is sent by theAI, and the authentication response is sent by the AR. The wirelesspower transmitter and receiver may be the AI or AR. For example, whenthe wireless power transmitter is the AI, the wireless power receiverbecomes the AR. On the contrary, when the wireless power receiver is theAI, the wireless power transmitter becomes the AR.

The authentication request message includes GET_DIGESTS (i.e., 4 bytes),GET_CERTIFICATE (i.e., 8 bytes), and CHALLENGE (i.e., 36 bytes).

The authentication response message includes DIGESTS (i.e., 4+32 bytes),CERTIFICATE (i.e., 4+Certificate Chain (3×512 bytes)=1540 bytes),CHALLENGE_AUTH (i.e., 168 bytes), and ERROR (i.e., 4 bytes).

The authentication message may be called an authentication packet,authentication data, and authentication control information. Inaddition, the GET_DIGEST message may be referred to as a GET_DIGESTpacket, and the DIGESTS message may be referred to as a DIGEST packet.

FIG. 15 illustrates an application-level data stream between a wirelesspower transmitter and receiver according to an embodiment of the presentdisclosure.

Referring to FIG. 15, a data stream may include an auxiliary datacontrol (ADC) data packet and/or an auxiliary data transport (ADT) datapacket.

The ADC data packet is used to open a data stream. The ADC data packetmay indicate the type of message included in the stream and the numberof data bytes. The ADT data packet is sequences of data including anactual message. An ADC/end data packet is used to notify the end of astream. For example, the maximum number of data bytes in a datatransport stream may be limited to 2047.

In order to inform whether the ADC data packet and ADT data packet arenormally received, an ACK or NACK is used. Control information requiredfor wireless charging such as a control error (CE) packet or DSR may betransmitted between the transmission timings of the ADC data packet andthe ADT data packet.

Based on the above data stream structure, authentication-relatedinformation or other application-level information may betransmitted/received between the wireless power transmitter andreceiver.

FIG. 16 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to an embodiment of the presentdisclosure.

Referring to FIG. 16, a wireless power receiver 1610 may include a firstOB communication module (first out-of-band (OOB) communication module)1611 and a first IB communication module 1612. A wireless powertransmitter 1620 may include a second OB communication module 1621 and asecond IB communication 1622.

Each of the first IB communication module 1612 and the second IBcommunication module 1622 may transmit or receive a packet based on acoil provided therein.

Each of the first OB communication module 1611 and the second OBcommunication module 1621 may transmit or receive a packet on ashort-range wireless communication antenna.

In an embodiment, each of the first OB communication module 1611 and thesecond OB communication module 1621 may be a BLE communication module,but the present disclosure is not limited thereto.

The first IB communication module 1612 may transmit a random addresspacket to the second IB communication module 1622 through IBcommunication (S1601).

The second IB communication module 1622 may transmit the received randomaddress (packet) to the second OB communication module 1621 (S1602).

The wireless power transmitter 1620 may update a whitelist based on therandom address (Whitelist Renewal) (S1603). Here, the whitelist may beupdated by the second OB communication module 1621. However, this ismerely an example, and the whitelist may be updated by a controller thatis provided in the wireless power transmitter 1620 and configured tocontrol wireless power transmission.

The second OB communication module 1621 may transmit a response signalto the wireless power receiver 1610 only when the wireless powerreceiver 1610 is included in the whitelist (No Response ExceptWhitelist) (S1604).

The wireless power transmitter 1620 in the embodiment of FIG. 16 maycorrespond to the wireless power transmitter or the power transmitterdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower transmitter 1620 in this embodiment may be performed by one of thecomponents of the wireless power transmitter in FIGS. 1 to 11 or acombination of two or more components. For example, the second IBcommunication module 1622 of the wireless power transmitter 1620 in thisembodiment may be equivalent to the IB communication module 121 of FIG.4C or 4D, and the second OB communication module 1621 of the wirelesspower transmitter 1620 may be equivalent to the OB communication module122 of FIG. 4C or 4D.

In addition, the wireless power receiver 1610 in the embodiment of FIG.16 may correspond to the wireless power receiver or the power receiverdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower receiver 1610 in this embodiment may be performed by one of thecomponents of the wireless power receiver in FIGS. 1 to 11 or acombination of two or more components. For example, the first IBcommunication module 1612 of the wireless power receiver 1610 in thisembodiment may be equivalent to the IB communication module 221 of FIG.4C or 4D, and the first OB communication module 1611 of the wirelesspower receiver 1610 may be equivalent to the OB communication module 222of FIG. 4C or 4D.

In another example, the wireless power transmitter 1620 may establishconnection with devices in the whitelist as shown in FIG. 17.

FIG. 17 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to another embodiment of the presentdisclosure.

Referring to FIG. 17, a wireless power receiver 1710 may include a firstOB communication module 1711 and a first IB communication module 1712. Awireless power transmitter 1720 may include a second OB communicationmodule 1721 and a second IB communication module 1722.

Each of the first IB communication module 1712 and the second IBcommunication module 1722 may transmit or receive a packet based on acoil provided therein.

Each of the first OB communication module 1711 and the second OBcommunication module 1721 may transmit or receive a packet on ashort-range wireless communication antenna.

In an embodiment, each of the first OB communication module 1711 and thesecond OB communication module 1721 may be a BLE communication module,but the present disclosure is not limited thereto. Specifically, any oneof the following technologies: Wi-Fi communication, radio frequencyidentification (RFID) communication, and Bluetooth communication may beapplied.

The second IB communication module 1722 may transmit a random addresspacket to the first IB communication module 1712 through IBcommunication (S1701).

The first IB communication module 1712 may transmit the received randomaddress (packet) to the first OB communication module 1711 (S1702).

The wireless power receiver 1710 may update a whitelist based on therandom address (Whitelist Renewal) (S1703). Here, the whitelist may beupdated by the first OB communication module 1711. However, this ismerely an example, and the whitelist may be updated by a controller orprocessor that is provided in the wireless power receiver 1710 andconfigured to control wireless power reception.

The first OB communication module 1711 may transmit a response signal tothe wireless power transmitter 1720 only when the wireless powertransmitter 1720 is included in the whitelist (No Response ExceptWhitelist) (S1704).

According to an embodiment, the wireless power receiver 1710 mayactively operate and manage the whitelist for wireless powertransmitters to prevent cross-connection.

The wireless power transmitter 1720 in the embodiment of FIG. 17 maycorrespond to the wireless power transmitter or the power transmitterdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower transmitter 1720 in this embodiment may be performed by one of thecomponents of the wireless power transmitter in FIGS. 1 to 11 or acombination of two or more components. For example, the second IBcommunication module 1722 of the wireless power transmitter 1720 in thisembodiment may be equivalent to the IB communication module 121 of FIG.4C or 4D. The second OB communication module 1721 of the wireless powertransmitter 1720 may be equivalent to the OB communication module 122 ofFIG. 4C or 4D.

In addition, the wireless power receiver 1710 in the embodiment of FIG.17 may correspond to the wireless power receiver or the power receiverdisclosed in FIGS. 1 to 11. Accordingly, the operation of the wirelesspower receiver 1710 in this embodiment may be performed by one of thecomponents of the wireless power receiver in FIGS. 1 to 11 or acombination of two or more components. For example, the first IBcommunication module 1712 of the wireless power receiver 1710 in thisembodiment may be equivalent to the IB communication module 221 of FIG.4C or 4D. The first OB communication module 1711 of the wireless powerreceiver 1710 may be equivalent to the OB communication module 222 ofFIG. 4C or 4D.

FIG. 18 is a flowchart illustrating operations of a wireless powertransmitter and receiver according to a further embodiment of thepresent disclosure.

Referring to FIG. 18, a wireless power receiver 1810 may include a firstOB communication module 1811 and a first IB communication module 1812. Awireless power transmitter 1820 may include a second OB communicationmodule 1821 and a second IB communication module 1822.

Each of the first IB communication module 1812 and the second IBcommunication module 1822 may transmit or receive a packet based on acoil provided therein.

Each of the first OB communication module 1811 and the second OBcommunication module 1821 may transmit or receive a packet on ashort-range wireless communication antenna.

In an embodiment, each of the first OB communication module 1811 and thesecond OB communication module 1821 may be a BLE communication module,but the present disclosure is not limited thereto. Specifically, any oneof the following technologies: Wi-Fi communication, RFID communication,and Bluetooth communication may be applied.

The first IB communication module 1812 may transmit a first randomaddress packet to the second IB communication module 1822 through IBcommunication (S1801).

The second IB communication module 1822 may transmit the received firstrandom address (packet) to the second OB communication module 1821(S1802).

The wireless power transmitter 1820 may update a first whitelist basedon the first random address (First Whitelist Renewal) (S1803). Here, thefirst whitelist may be updated by the second OB communication module1821. However, this is only an example, and the first whitelist may beupdated by a controller or processor provided in the wireless powertransmitter 1820 and configured to control wireless power transmission.

The wireless power transmitter 1820 may transmit a second random addresspacket to the first IB communication module 1812 through the second IBcommunication module 1822 (S1804).

The first IB communication module 1812 may transmit the received secondrandom address to the first OB communication module 1811 (S1805).

The wireless power receiver 1810 may update a second whitelist based onthe second random address (Second Whitelist Renewal) (S1806). Here, thesecond whitelist may be updated by the first OB communication module1811. However, this is only an example, and the second while list may beupdated by a controller or processor provided in the wireless powerreceiver 1810 and configured to control wireless power reception.

The first OB communication module 1811 may transmit a response signal tothe wireless power transmitter 1820 only when the wireless powertransmitter 1820 is included in the second whitelist, and the second OBcommunication module 1821 may transmit a response signal to the wirelesspower receiver 1810 only when the wireless power receiver 1810 isincluded in the first whitelist. The wireless power receiver 1810 andthe wireless power transmitter 1820 may perform direct connection basedon the first and second whitelists. (No Response Except Whitelist orDirect Connection) (S1807).

In the embodiment of FIG. 18, the wireless power receiver 1810 and thewireless power transmitter 1820 may establish connection with a deviceexisting in their whitelists.

In another example, the wireless power transmitter 1820 may establishconnection only with specific peer device(s) designated by the hostand/or devices in its own whitelist (i.e., wireless power receivers).

In this way, the wireless power transmitter may prevent cross-connectionby managing the whitelist for wireless power receivers. Thecross-connection prevention may also be performed by the wireless powerreceiver. That is, the wireless power transmitter and the wireless powerreceiver may perform a cross check based on whitelist(s) to prevent thecross-connection.

The wireless power transmitter 1820 in the embodiment of FIG. 18 maycorrespond to the wireless power transmitter or the power transmitterdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower transmitter 1820 in this embodiment may be performed by one of thecomponents of the wireless power transmitter in FIGS. 1 to 11 or acombination of two or more components. For example, the second IBcommunication module 1822 of the wireless power transmitter 1820 in thisembodiment may be equivalent to the IB communication module 121 of FIG.4C or 4D. The second OB communication module 1821 of the wireless powertransmitter 1820 may be equivalent to the OB communication module 122 ofFIG. 4C or 4D.

The wireless power receiver 1810 in the embodiment of FIG. 18 maycorrespond to the wireless power receiver or the power receiverdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower receiver 1810 in this embodiment may be performed by one of thecomponents of the wireless power receiver in FIGS. 1 to 11 or acombination of two or more components. For example, the first IBcommunication module 1812 of the wireless power receiver 1810 in thisembodiment may be equivalent to the IB communication module 221 of FIG.4C or 4D. The first OB communication module 1811 of the wireless powerreceiver 1810 may be equivalent to the OB communication module 222 ofFIG. 4C or 4D.

FIG. 19 is a block diagram illustrating state machines for PC0 and PC1according to an embodiment of the present disclosure.

Hereinafter, a device filtering policy will be described.

Based on device filtering, a link manager may be configured to respondonly to a specific set of devices (i.e., whitelist). That is, the linkmanager may ignore transmission or requests from devices not included inthe whitelist.

For example, the device filtering may include an operation of respondingto devices with MAC addresses in the whitelist and not responding todevices (advertisers, scanners, initiators, etc.) with MAC addresses outof the whitelist. The device filtering may be performed or managed underspecific rules defined for each phase, such as advertising, scanning,and initiating.

First, advertisement filtering rules define how the LL of an advertiserprocesses scan requests and connection requests. For example, the LL ofthe advertiser may be configured to process scan requests or connectrequests from devices in the whitelist. In another example, the LL ofthe advertiser may be configured to process scan requests received fromall devices but process connection requests received from devices in thewhitelist. In a further example, the LL of the advertiser may beconfigured to process connection requests from all devices but processscan requests received from devices in the whitelist.

Next, scanner filtering rules define how the LL of a scanner processesadvertisement packets. For example, the LL of the scanner may processadvertisement packets received from devices in the whitelist.

Finally, initiator filtering rules define how the LL of an initiatorprocesses advertisement packets. For example, the LL of the scanner mayprocess reachable advertisement packets from devices in the whitelist.

The privacy function of BLE may be implemented so that a device may hidea real address. In this case, the device may perform communication basedon a random address rather than the real address. The random address maychange over time. The random address may include the following two typesof addresses.

(1) Static Address

The device may perform (or select) an operation of initializing thestatic address of the device to a new value after each power cycle.However, the device may not change the static address within a powercycle.

(2) Private Address

The private address may include a non-resolvable private address and aresolvable private address.

For the non-resolvable private address, a peer device may not discover areal address corresponding to the non-resolvable used address.

For the resolvable private address, the peer device may derive the realaddress corresponding to the resolvable used address based on the randomaddress and/or the link key of connection.

According to the state machines according to FIG. 19, OB communicationmay be limited by a state machine corresponding to IB communication.Accordingly, information exchange through the IB communication isessential in configuration and negotiation phases. Thus, time delayoverhead may occur during handover from the IB communication to the OBcommunication, and the charging start time may slightly increase.

According to one embodiment, if a wireless power transmitter andreceiver have a previous OB communication connection record and knoweach other's configuration information (e.g., MAC address information,etc.), the wireless power transmitter and receiver may store theprevious connection record and configuration information in thewhitelist. In this case, devices (wireless power transmitter and/orwireless power receiver) stored in the whitelist may skip steps requiredfor the handover to the OB communication (i.e., steps based on the IBcommunication) and directly perform the handover from IB to OB. (i.e.,OB communication connection establishment). The above handover may bereferred to as handover for reconnection.

The wireless power transmitter and receiver may exchange packets throughthe OB communication from a phase after the handover is completed.

The wireless power transmitter and/or receiver may determine thedistance between the wireless power transmitter and receiver by using areceived signal strength indicator (RSSI) value or a direct findingmethod based on the OB communication. In this case, if the RSSI value isabove a predetermined level (that is, when a predetermined condition issatisfied), the wireless power transmitter and/or receiver may enter ahandover phase for reconnection with devices included in the whitelistand attempt the reconnection.

In the state machines according to FIG. 19, there is a problem in thatonly one opportunity is given for the handover to the OB during acharging cycle and subsequent reconnection is impossible.

However, the 2.4 GHz band used for BLE communication is largelyallocated to other communication, and thus, there may be significantinterference between a BLE signal for wireless charging and othersignals. If there is a problem in BLE connection in an environment wherethere is significant interference to OB frequencies for wirelesscharging, that is, when the handover to the OB fails, opportunities forOB reconnection are required.

Embodiments

In the following embodiments, even if handover from IB communication toOB communication fails, a wireless power transmitter (or wireless powerreceiver) may check whether the wireless power receiver (or wirelesspower transmitter) supports the OB communication (e.g., BLEcommunication) and then attempt reconnection.

In one aspect, the wireless power transmitter (or wireless powerreceiver) may store whether the wireless power receiver (or wirelesspower transmitter) supports the OB communication.

In another aspect, the wireless power transmitter (or wireless powerreceiver) may store the connection state of the OB communication of thewireless power receiver (or wireless power transmitter).

In a further aspect, the wireless power transmitter (or wireless powerreceiver) may store whether the wireless power receiver (or wirelesspower transmitter) supports the OB communication and the connectionstate of the OB communication.

In this case, whether the OB communication is supported and/or theconnection state of the OB communication may be stored in a powercontract between the wireless power transmitter and the wireless powerreceiver. When the state is changed, the power contract may be renewed.When the connection state of the OB (i.e., BLE) communication ischanged, the wireless power transmitter and the wireless power receivermay enter a renegotiation phase to renew the power contract.

The wireless power receiver (or wireless power transmitter) may attemptthe handover to the OB communication based on a MAC address packet atall phases of the state machine.

For example, the wireless power receiver (or wireless power transmitter)may transmit a MAC address packet to the wireless power transmitter (orwireless power receiver) through the IB communication at all phases ofthe state machine, and the wireless power receiver (or wireless powertransmitter) may attempt the handover to the OB based on the receivedMAC address.

FIG. 20 is a diagram for explaining a method of adding information onwhether OB (i.e., BLE) is supported and information on a connectionstate to a power contract according to an embodiment of the presentdisclosure.

Referring to FIG. 20, an initial power transfer contract 2000 includesthe following parameters: guaranteed power, maximum power, receivedpower packet format, FSK polarity and modulation depth, and BLE status.In particular, the BLE status parameter may include information onwhether BLE is supported and information on a BLE connection state asshown in reference numeral 2010.

FIG. 21 is a flowchart illustrating a procedure for renewing a powertransfer contract according to an embodiment of the present disclosure.

The power transfer contract renewal procedure according to theembodiment of FIG. 21 may be performed by a wireless power transmitteror receiver.

Hereinafter, a wireless power transmitter or receiver is collectivelyreferred to as a wireless charger for convenience of description.

Referring to FIG. 21, a wireless charger may check whether a wirelesspower receiver (or wireless power transmitter) supports OB communicationbased on a handover flag in a configuration phase (S2101). For example,the handover flag may be included in a configuration packet. When thehandover flag of the configuration packet received from the wirelesspower receiver is TRUE, the wireless power transmitter may confirm thatthe wireless power receiver supports the OB communication. In addition,when the handover flag of the configuration packet received from thewireless power transmitter is TRUE, the wireless power receiver mayconfirm that the wireless power transmitter supports the OBcommunication. Although this embodiment describes that the handover flagis included in the configuration packet, it is merely an example. Inanother embodiment, the handover flag may be configured to betransmitted through other packets transmitted and received at otherphases of the state machine. For example, the handover flag may bereceived in a negotiation phase, and the wireless charger may generateand store an initial power transfer contract after the negotiation phaseand enter a handover phase.

After the configuration phase, the wireless charger may write and storethe initial power transfer contract including whether the wireless powerreceiver (or wireless power transmitter) supports the OB communicationand/or the connection state of the OB communication (or whether the OBcommunication is connected) (Initial Power Transfer Contract) (S2102).For example, in the initial power transfer contract, the connectionstate of the OB communication may be set to FALSE, and whether the OBcommunication is supported may be set to TRUE.

After writing and storing the initial power transfer contract, thewireless charger may enter the handover phase to attempt handover to theOB when whether the wireless power receiver (or wireless powertransmitter) supports the OB is set to TRUE (S2103).

The wireless charger may determine whether the handover (i.e., OBcommunication connection) is successful (Handover Success?) (S2014).When the OB communication connection between the wireless powertransmitter and the wireless power receiver fails in the handover phase,the wireless charger may maintain the initial power transfer contractwithout any renewal (S2106). Accordingly, the connection state of the OBcommunication of the wireless power receiver (or wireless powertransmitter) is FALSE, and whether the OB is supported is continuouslymaintained as TRUE.

Even when the handover fails in step S2104, the wireless charger mayreattempt the OB connection (Retry Connection) (S2107). In this case,the wireless power transmitter and/or the wireless power receiver mayattempt the OB connection separately or independently from the statemachine. According to an embodiment, in step S2107, the wireless chargermay attempt OB reconnection for a predetermined number of times untilthe handover to the OB is successful. If the wireless charger fails inthe OB connection the predetermined number of times, the wirelesscharger may enter a predefined state machine phase, for example, aselection phase.

According to another embodiment, in step S2107, the wireless charger mayattempt the OB reconnection for a predetermined time until the handoverto the OB is successful. If the wireless charger fails in the OBconnection until the expiration of the predetermined time, the wirelesscharger may enter a predefined state machine phase, for example, aselection phase.

For example, the wireless charger may attempt reconnection at apredetermined time period.

If the wireless charger succeeds in the OB connection after thereconnection attempt in step S2107, the wireless charger may enter arenegotiation phase (or a next phase after the last IB state machine)(Renegotiation Phase or Next Phase) (S2108) to renew the power transfercontract. (Power Transfer Contract Renewal) (S2109). In this case, inthe renewed power transfer contract, the connection state of OBcommunication may be set to TRUE, and whether the OB support may be setto TRUE.

According to an embodiment, the power transfer contract may be performedat any phases other than the renegotiation phase. That is, the wirelesscharger may check the connection state of the OB communication of thewireless power transmitter or receiver based on the power transfercontract at the beginning of each phase step and then attempt thehandover to the OB or the OB communication connection if the OBconnection is enabled. Alternatively, the wireless charger mayperiodically check whether the power transfer contract is renewed duringa power transfer phase.

The wireless power transmitter in the embodiments of FIG. 21 maycorrespond to the wireless power transmitter or the power transmitterdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower transmitter in the embodiments may be performed by one of thecomponents of the wireless power transmitter in FIGS. 1 to 11 or acombination of two or more components. For example, an OB (BLE)communication module of the wireless power transmitter in thisembodiment may be equivalent to the OB communication module 122 of FIG.4C or 4D.

The wireless power receiver in the embodiments of FIG. 21 may correspondto the wireless power receiver or the power receiver disclosed in FIGS.1 to 11. Accordingly, the operations of the wireless power receiver inthis embodiment may be performed by one of the components of thewireless power receiver in FIGS. 1 to 11 or a combination of two or morecomponents. For example, an OB (BLE) communication module of thewireless power receiver in this embodiment may be equivalent to the OBcommunication module 222 of FIG. 4C or 4D.

FIG. 22 is a flowchart illustrating a procedure for renewing a powertransfer contract according to another embodiment of the presentdisclosure.

In the embodiment of FIG. 22, it is assumed that in FIG. 21, a wirelesspower transmitter (or wireless power receiver) enters a handover phaseto attempt handover to OB communication when whether the wireless powerreceiver (or wireless power transmitter) supports the OB communicationis set to TRUE.

If the wireless power transmitter (or wireless power receiver) fails inOB connection in the handover phase, the wireless power transmitter (orwireless power receiver) may attempt the OB connection continuously,periodically, a predetermined number of times, and/or for apredetermined time.

The power transfer contract renewal procedure according to theembodiment of FIG. 22 may be performed by the wireless power transmitteror receiver.

Hereinafter, a wireless power transmitter or receiver is collectivelyreferred to as a wireless charger for convenience of description.

Referring to FIG. 22, the wireless charger may periodically transmit anaddress packet to the wireless power transmitter (or wireless powerreceiver) in order to attempt the handover to the OB (S2210).

Here, the address packet may include the MAC address of the wirelesspower receiver (or wireless power transmitter).

For example, the MAC address may be a random address.

In another example, the address packet may be transmitted through IBcommunication.

In a further example, the address value is randomly changed whenever aMAC address packet is transmitted, thereby preventing tracking. Forexample, the wireless power receiver may transmit the MAC address packetto the wireless power transmitter when the wireless power receiver failsin the handover to the OB. In this case, the MAC address packet mayinclude another MAC address that is randomly selected (or generated)other than the existing MAC address.

The wireless charger may determine whether the handover is successful(S2220).

For example, after transmitting the MAC address packet to the wirelesspower transmitter (or wireless power receiver), the wireless charger maytransmit an advertisement packet to the corresponding address for apredetermined time to attempt OB (i.e., BLE) communication connection.If the wireless charger succeeds in the OB communication connection, thewireless charger may determine that the handover is successful.

If the wireless charger succeeds in the handover, the wireless chargermay renew the power transfer contract (Power Transfer Contract Renewal)(S2230).

For example, if the handover is successful, the wireless charger mayenter a renegotiation phase to renew the power transfer contract.

In another example, if the handover is successful, the wireless chargermay renew the power transfer contract by entering the last state machinephase before entering the handover phase. For example, if the wirelesscharger succeeds in the handover after transitioning from the powertransfer phase of the IB to the handover phase, the wireless charger mayreturn to the power transfer phase and renew the power transfercontract. In another example, if the wireless charger succeeds in thehandover after transitioning from the negotiation phase of the IB to thehandover phase, the wireless charger may return to the power transferphase and renew the power transfer contract.

In a further example, if the handover is successful, the wirelesscharger may renew the power transfer contract by entering the next phaseof the last state machine before entering the handover phase. Forexample, if the wireless charger succeeds in the handover aftertransitioning from a configuration and identification phase to thehandover phase, the wireless charger may enter the negotiation phase torenew the power transfer contract.

FIG. 23 illustrates a timeout procedure in case of packet loss.

Referring to FIG. 23, an IB timeout and an OB timeout may be differentlymanaged in WPC. First, for the IB timeout, if a wireless powertransmitter does not correctly receive the start of a new CE packet 2320within t_(timeout) after the start of a previous CE packet 2310, thewireless power transmitter may remove a power signal withint_(terminate).

For the OB timeout, a link supervision timeout parameter is used by acontroller configured to monitor link loss. If, for any reason, nopackets are received for a period longer than a link supervisiontimeout, the connection may be released.

In this case, the following disadvantages may occur: independence isrequired between a wireless power transmission module and acommunication module; and a state machine is initialized when acommunication error occurs.

According to an embodiment, a wireless power transmitter and/or receivermay include a plurality of communication modules and selectively use theplurality of communication modules.

For example, two communication modules may be provided in the wirelesspower transmitter, and two communication modules may be provided in thewireless power receiver. In this case, one of the two communicationmodules provided in the wireless power transmitter and/or receiver maybe an IB communication module, and the other one may be an OBcommunication module.

In another example, three communication modules may be provided in thewireless power transmitter, and two communication modules may beprovided in the wireless power receiver. In this case, the wirelesspower transmitter may include one IB communication module and twodifferent OB communication modules, and the wireless power receiver mayinclude one IB communication module and one OB communication module.

In a further example, three communication modules may be provided in thewireless power transmitter and receiver. In this case, one communicationmodule may be an IB communication module and two communication modulesmay be OB communication modules. The two OB communication modules maysupport different data transmission rates.

The wireless power transmitter and receiver may perform communication byadaptively selecting an optimal communication module based on channelquality and required power for each communication module.

FIG. 24 is a functional block diagram of a wireless power transmitter orreceiver according to an embodiment of the present disclosure.

Referring to FIG. 24, the wireless power transmitter or receiver mayperform a power control function, a state machine function, an FODfunction, and so on. Here, the functions may be implemented by hardwaresuch as circuit components, microprocessors, and memories as well assoftware.

The wireless power transmitter and/or receiver may include an IBcommunication module and an OB communication module. The IBcommunication module may perform the power control function, statemachine function, FOD function, etc. The OB communication module mayperform the power control function, state machine function, FODfunction, etc.

The wireless power transmitter and/or receiver may select any one of theIB communication module and the OB communication module and perform thepower control function, state machine function, FOD function, etc. basedon the selected communication module.

The wireless power transmitter in the embodiments of FIG. 24 maycorrespond to the wireless power transmitter or the power transmitterdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower transmitter in the embodiments may be performed by one of thecomponents of the wireless power transmitter in FIGS. 1 to 11 or acombination of two or more components. For example, the IB communicationmodule of the wireless power transmitter in the embodiments may beequivalent to the IB communication module 121 of FIG. 4C or 4D, and theOB communication module of the wireless power transmitter in theembodiments may be equivalent to the OB communication module 122 of FIG.4C or 4D.

The wireless power receiver in the embodiments of FIG. 24 may correspondto the wireless power receiver or the power receiver disclosed in FIGS.1 to 11. Accordingly, the operations of the wireless power receiver inthe embodiments may be performed by one of the components of thewireless power receiver in FIGS. 1 to 11 or a combination of two or morecomponents. For example, the IB communication module of the wirelesspower receiver in the embodiments may be equivalent to the IBcommunication module 221 of FIG. 4C or 4D, and the OB communicationmodule of the wireless power receiver in the embodiments may beequivalent to the OB communication module 222 of FIG. 4C or 4D.

According to another embodiment, the wireless power transmitter and/orreceiver may change the communication (i.e., handover) from IBcommunication to OB communication.

FIG. 25 is a flowchart illustrating a procedure in which a wirelesspower transmitter and/or wireless power receiver changes communicationfrom IB communication to OB communication according to an embodiment ofthe present disclosure.

Hereinafter, a wireless power transmitter and/or receiver iscollectively referred to as a wireless charger for convenience ofdescription.

Referring to FIG. 25, the wireless charger may perform packet monitoringto determine whether there occurs a timeout (S2510). Upon detecting thetimeout, the wireless charger may determine whether the wireless powertransmitter and/or receiver supports OB communication (OOB Support?)(S2520). For example, the timeout may be for IB communication. However,this is merely an example, and the timeout may be for the OBcommunication.

When it is determined that the OB communication is supported, thewireless charger may determine whether the OB (i.e., BLE) communicationis connected (Connected State?) (S2530). Here, whether the OBcommunication is supported and whether the OB communication is connectedmay be specified or recorded in a power transfer contract.

For example, whether the OB communication is supported may berepresented by as TRUE or FALSE. Depending on whether the OBcommunication is supported and/or whether the OB communication isconnected, the wireless charger may perform subsequent operations.

If it is determined in step S2520 that the OB communication is notsupported, the wireless charger may stop power transfer and enter aselection phase (Terminate Power & Go to Selection Phase) (S2590).

The wireless charger may determine whether the OB communication issupported and whether the OB communication is connected as either TRUE(YES) or FALSE (NO).

When the OB communication connection is TRUE, the wireless charger maytransmit a write request signal requesting to change the communicationand wait for reception of a response signal (S2540).

Upon receiving the response signal, the wireless charger may switch fromthe IB communication to the OB communication (S2560). In this case, thewireless charger may update the OB communication connection state of thepower transfer contract from FALSE to TRUE. If the wireless chargerreceives no response signal, the wireless charger may terminate thepower transfer and enter the selection phase.

For example, when the wireless power receiver (or wireless powertransmitter) supports the OB communication and the OB communication isconnected (when OOB Support=Yes (TRUE) and Connected State=Yes (TRUE)),the wireless power transmitter (or wireless power receiver) may requestthe wireless power receiver (or wireless power transmitter) to changethe communication (handover to the OB communication) based on the writecharacteristics (i.e., Write Request). Thereafter, the wireless powertransmitter (or wireless power receiver) may wait for a write responsefrom the wireless power receiver (or wireless power transmitter) (Waitfor Response). If the wireless power transmitter (or wireless powerreceiver) receives the write response from the wireless power receiver(or wireless power transmitter) (Response=Yes), the wireless powertransmitter (or wireless power receiver) may change the communication tothe OB communication (Change Communication to OOB) and wait for a nextWPC packet through the OB communication. After transmitting the writeresponse, the wireless power receiver (or wireless power transmitter)may generate a WPC packet according to the OB communication and transmitthe WPC packet to the wireless power transmitter (or wireless powerreceiver) based on the OB communication. If the wireless powertransmitter (or wireless power receiver) receives no write response fromthe wireless power receiver (or wireless power transmitter)(Response=No), the wireless power transmitter (or wireless powerreceiver) may stop the power transfer and initialize the state machineto enter the selection phase (Terminate Power & Go to Selection Phase).

In step S2530, if the OB communication connection state is FALSE, thewireless charger may enter a handover phase for performing areconnecting procedure (S2570).

The wireless charger may determine whether the OB communicationconnection is successful by performing the OB reconnecting procedure(Connection Success?) (S2580).

If it is determined that the OB communication connection is successful,the wireless charger may change the communication to the OBcommunication and update the OB communication connection state of thepower transfer contract from FALSE to TRUE (S2560).

If it is determined in step S2580 that the OB communication connectionfails, the wireless charger may enter step S2590.

For example, when the wireless power transmitter (or wireless powerreceiver) supports the OB communication but the OB communicationconnection is not established (OOB Support=Yes and Connected State=No),the wireless power transmitter (or wireless power receiver) may enterthe handover phase and perform a reconnection procedure (Handover forReconnection Procedure). Thereafter, the wireless power transmitter (orwireless power receiver) may determine whether the OB communicationconnection is successful (Connection Success?). If the OB communicationconnection is successful (Connection Success=Yes), the wireless powertransmitter (or wireless power receiver) may change the communication tothe OB communication (Change Communication to GOB). If the wirelesspower transmitter (or wireless power receiver) eventually fails in theOB communication connection despite performing the reconnectingprocedure, the wireless power transmitter (or wireless power receiver)may stop transmitting power (or receiving power), initialize the statemachine, and enter the selection phase (Terminate Power & Go toSelection Phase).

FIG. 26 is a flowchart for explaining a method by which a wireless powertransmitter and/or wireless power receiver controls communicationconnection according to another embodiment of the present disclosure.

Hereinafter, a wireless power transmitter and/or receiver iscollectively referred to as a wireless charger for convenience ofdescription.

Referring to FIG. 26, the wireless charger may perform packet monitoringto determine whether there occurs a timeout (Timeout Detection) (S2510).For example, the timeout may be for OB communication. However, this ismerely an example, and the timeout may be for IB communication. Forexample, when the OB communication is BLE communication, the timeout maybe a supervision timeout of the BLE communication.

When the wireless charger detects the timeout, the wireless charger maymeasure the level of current transmitted (or received) power and checkwhether the measured level of the transmitted (or received) power is PC1or exceeds a first reference power level, for example, 40 watts (W)(S2620). Here, the first reference power level is set to 40 W, but thisis merely an example. The power consumption (or required power) of adevice supporting PC1 may vary depending on the type and kind ofcharging target device such as a laptop, an electric drill, or a drone,and thus, the first reference power level may vary depending on thepower consumption.

If the power class corresponding to the level of the current transmitted(or received) power is PC1 or if the level of the current transmitted(or received) power is higher than or equal to a specific power level(e.g., 40 W), the wireless charger may perform an operation of limitingthe transmitted (or received) power to a second reference power level,for example, 15 W or less or an operation of changing the power classfrom PC1 to PC0 (Power Down under 15 W OR PC1->PC0) (S2630).

The wireless charger may enter a handover phase after lowering the powerlevel based on the timeout (S2640).

For example, the wireless charger may attempt OB communicationconnection to resume power transmission of 40 W or more, i.e., PC1 powertransfer.

The wireless charger may enter the handover phase and perform areconnection procedure (S2650). Here, the reconnecting procedure maymean a communication connecting procedure for reconnecting to the OBcommunication.

The wireless charger may determine whether the OB communicationconnection is successful through the reconnecting procedure (ConnectionSuccess?) (S2660).

If the OB communication connection is successful, the wireless chargermay switch to the OB communication and control power transmission (orreception) to be higher than or equal to 40 W (Power Up above 40 W) orchange the power class from PC0 to PC1 (S2670).

In step S2620, if the transmitted (or received) power level is out ofPC1 and less than or equal to the first reference power, the wirelesscharger may enter the handover phase without performing an operation oflowering the power level (S2630).

In step S2660, if the wireless charger fails in the OB communicationconnection, the wireless charger may maintain an operation of limitingthe power level to 15 W or less and enter step S2650 to attempt the OBcommunication connection again.

When there occurs a timeout, the wireless power transmitter may replacethe communication module with an IB communication module and transmitpower of 40 W or more based on the IB communication according to thechoice of the manufacturer, instead of limiting the power transfer.

The wireless power transmitter may attempt OB reconnection by reenteringthe handover phase periodically while maintaining the power transmissionof 40 W or more through the IB communication module.

In an embodiment, the wireless power transmitter and/or receiver mayenter the handover phase at any phase of the state machine and attemptthe OB reconnection.

In an embodiment, the wireless power transmitter and/or receiver maydrive the state machine and the communication module independently sothat the communication module may attempt the OB reconnection regardlessof the state machine phase and renew a power transfer contract dependingon the success or failure of the OB reconnection.

In an embodiment, when the wireless power transmitter and/or receiverdiscovers a device in a whitelist, the wireless power transmitter and/orreceiver may perform handover to OB regardless of the current statemachine phase.

In an embodiment, the wireless power transmitter and/or receiver mayswitch to the OB communication when an IB communication error occurs.The wireless power transmitter and/or receiver may switch to the IBcommunication when an OB communication error occurs. When there areerrors in both the IB and OB communication, the wireless powertransmitter and/or receiver may out a predetermined warning alarm andinitialize the state machine.

In an embodiment, the wireless power transmitter and/or receiver maysimultaneously maintain the IB communication and OB communication for apredetermined time after entering the handover phase. In this case,separate packets may be transmitted and received through the IBcommunication and OB communication.

In an embodiment, the wireless power transmitter and/or receiver mayseparate packets to be transmitted and received through the IBcommunication and OB communication based on at least one of the types,characteristics, sizes, usages, and periodicities of the packets.

In an embodiment, the wireless power transmitter and/or receiver maymaintain information on the statistics on the number of OB connectionattempts and success rates, block the OB connection based on thestatistical information, or notify a peer device that the OB is notsupported. Accordingly, the wireless power transmitter and/or receivermay prevent an unnecessary OB connection attempt in advance when the OBcommunication module fails, thereby minimizing power (or battery)consumption.

The wireless power transmitter according to the embodiments of FIGS. 25and 26 may correspond to the wireless power transmitter or the powertransmitter disclosed in FIGS. 1 to 11. Accordingly, the operations ofthe wireless power transmitter in the embodiments may be performed byone of the components of the wireless power transmitter in FIGS. 1 to 11or a combination of two or more components. Specifically, the change ofthe communication of the wireless power transmitter and procedures andoperations related thereto may be performed by the communication andcontrol unit 120.

The wireless power receiver according to the embodiments of FIGS. 25 and26 may correspond to the wireless power receiver or the power receiverdisclosed in FIGS. 1 to 11. Accordingly, the operations of the wirelesspower receiver in the embodiments may be performed by one of thecomponents of the wireless power receiver in FIGS. 1 to 11 or acombination of two or more components. Specifically, the change of thecommunication of the wireless power receiver and procedures andoperations related thereto may be performed by the communication andcontrol unit 220.

The steps of the methods or algorithms described in relation to theembodiments disclosed herein may be directly implemented by hardware andsoftware modules that are executed by a processor or may be directlyimplemented by a combination thereof. The software module may reside ina storage medium (i.e., memory and/or storage) such as a RAM, flashmemory, ROM, EPROM, EEPROM, register, hard disk, removable disk, orCD-ROM.

For example, the storage medium may be coupled to the processor, and theprocessor may read and write information from and to the storage medium.Alternatively, the storage medium may be integral with the processor.The processor and storage medium may reside within an applicationspecific integrated circuit (ASIC). The ASIC may reside within a userterminal. Alternatively, the processor and storage medium may reside asseparate components within the user terminal.

The above description is merely illustrative of the technical idea ofpresent disclosure, and various modifications and variations may be madewithout departing from the essential characteristics of presentdisclosure by those with ordinary knowledge in the technical field towhich present disclosure belongs.

Therefore, the embodiments disclosed in the present disclosure areintended to illustrate rather than to limit the technical idea of thepresent disclosure, and the scope of the technical idea of the presentdisclosure is not limited by these embodiments. The scope of protectionof the present disclosure should be construed according to the followingclaims, and all technical ideas within the scope equivalent theretoshould be construed as falling within the scope of the presentdisclosure.

INDUSTRIAL APPLICABILITY

The present disclosure may be applied to a wireless power transmitterfor wirelessly transmitting power, a wireless power receiver forwirelessly receiving power, and a wireless charging system using thesame.

1. A method of controlling a communication connection by a wirelesscharger supporting in-band communication and out-band communication, themethod comprising: receiving a first packet from a device through thein-band communication; creating a power transfer contract based on thefirst packet; establishing an out-band communication connection based onthe power transfer contract; and performing power control through theout-band communication based on success of the out-band communicationconnection.
 2. The method of claim 1, comprising: performing handover toout-band by entering a handover phase according to the power transfercontract; and maintaining the power transfer contract and performing anout-band reconnection procedure based on failure of the handover.
 3. Themethod of claim 2, wherein the out-band reconnection procedurecomprises: receiving a second packet including a random address from thedevice through the in-band communication; and registering the devicerelated to the random address in a whitelist, and wherein the out-bandreconnection procedure is performed with a device included in thewhitelist.
 4. The method of claim 3, wherein the out-band reconnectionprocedure is periodically repeated.
 5. The method of claim 1, whereinthe first packet includes a handover flag, and wherein the first packetis received in a configuration phase of a state machine.
 6. The methodof claim 5, wherein the power transfer contract includes information onwhether the device supports the out-band communication and informationon an out-band communication connection state, wherein whether theout-band communication is supported is determined based on the handoverflag, and wherein the power transfer contract is renewed based on thesuccess of the out-band communication connection.
 7. The method of claim6, wherein the power transfer contract is renewed in a renegotiationphase of the state machine.
 8. The method of claim 1, wherein theout-band communication is Bluetooth Low Energy (BLE) communication. 9.The method of claim 2, comprising: detecting a timeout of the out-bandcommunication; determining whether the device supports the out-bandcommunication based on the power transfer contract; determining anout-band communication connection state with the device based on thepower transfer contract; and performing the out-band reconnectionprocedure based on the out-band communication being supported and theout-band communication being not connected, wherein based on theout-band communication being not supported, charging is stopped and thestate machine is initialized.
 10. The method of claim 9, comprising:transmitting a write request packet requesting to change communicationbased on the out-band communication being supported and the out-bandcommunication being connected; and switching to the out-bandcommunication based on reception of a response packet for the writerequest packet, wherein the charging is stopped and the state machine isinitialized based on the response packet being not received.